شیخ مفید در ذیقعده سال ۳۳۶ (قمری) در نزدیکی بغداد متولد شد. او استاد شیخ طوسی و سید مرتضی علمالهدی بود. او فقیه و کلامی شیعی بود که بسیار در علم کلام تبحر داشت و مکتب کلامی شیعه در عصر او به اوج کمال رسید.
او مورد تحسین و احترام بزرگان اهل تسنن از قبیل، ابن حجر عسقلانی، ابن عماد حنبلی، شافعی و دیگران بود. شیخ طوسی درباره او در الفهرست مینویسد: «محمد بن محمد بن نعمان، معروف به ابن المعلم (ابوالعلی معری این لقب را به وی داده)، از متکلمان امامیه است. درعصر خویش ریاست و مرجعیت شیعه به او منتهی گردید. در فقه و کلام بر هر کس دیگر مقدم بود. حافظه خوب و ذهن دقیق داشت و در پاسخ به سؤالات حاضر جواب بود. او بیش از ۲۰۰ جلد کتاب کوچک و بزرگ دارد.»
معروفترین شاگردان او عبارتند از:
Abu 'Abd Allah Muhammad ibn Muhammad ibn al-Nu'man al-'Ukbari al-Baghdadi known as al-Shaykh al-Mufid and Ibn al-Mu'allim for his expertise in philosophical theology (c. 948-1022 CE) was an eminent Twelver Shi'a theologian. 
Al-Shaykh Al-Mufid was born on 11th Dhul Qa'dah, 336 Hijra (or 338 A.H. according to Sheikh Tusi) in 'Ukbara, a small town to the north of Baghdad  and later migrated together with his father to Baghdad, where the Shiite Buwayhids were ruling. In Shi'ite tradition, he studied with the famed traditionist al-Shaykh al-Saduq Ibn Babawayh al-Qummi. Prominent students of his included Sharif al-Murtaza, al-Shaykh al-Tusi, commonly known as the leader of the Shi'a and al-Karajaki. His career coincided with that of the famous Mu'tazili theologian and leader of the Bahshamiyya school, 'Abd al-Jabbar al-Asadabadi al-Hamadhani and with the disputations and intra-sectarian conflicts in Baghdad. He was thus often attacked and his library and school was destroyed. But he remained a faithful and significant intellectual defender of Twelver Shi'ism and was respected by friends and opponents.
Al-Mufid is quite often accused of incorporating the modes of theological reasoning common in the Baghdad school of the Mu'tazila as exemplified by his teacher Abu'l-Qasim al-Ka'bi al-Balkhi into Twelver Shi'ite theology. This is however on the basis of studies relying on a Sunni interpretation of Shi'ite theological history. The Shi'ite interpretation is that the Mu'tazila borrowed from the Imams long before al-Mufid and the Shi'ah doctrine was already in place at the time al-Mufid. 
Al-Mufid died on the eve of Friday, 3rd of Ramadan, 413 A.H. His student Sayyid al-Murtada led his funeral prayer(Salat-e-Mayyit), in the presence of nearly eighty thousand people, a crowd never seen before in any funeral in Baghdad.
Shaykh Tusi (d. 460 A.H.) describes this sad event in al-Fihrist:
"The day of his death drew the largest crowd ever seen in any funeral, and both, friends and foes, wept uncontrollably".
Al-Mufid remained buried in his own house for two years, and then his body was transferred to Al Kadhimiya Mosque where it was interred near his mentor, Ja'far ibn Qawlayh's grave facing the feet of Imam Muhammad at-Taqi. His grave is still visited by those who visit the holy shrines in Kadhimayn.
How Al-Mufid was named
It is said that al-Mufid earned his title of al-Mufid as a result of a dispute about the relative merits of the two events - Ghadir Khumm and the Cave. The story goes that when al-Mufid - Abu 'Abd Allah as he was - went to visit the scholar 'Ali b. 'Isa al-Ramani, mentioned above, there was a great crowd of people with the scholar. When the crowd grew thinner, the young Abu 'Abd Allah approached the scholar. However, then the arrival of a man from Basra was announced. The two, that is 'Ali b. 'Isa and his visitor from Basra, spoke for some time. Then the visitor asked 'Ali b. 'Isa what he had to say about the events of Ghadir Khumm and the Cave. 'Ali b. 'Isa replied:
"The tradition of the Cave is definite knowledge (diraya) while the tradition of Ghadir is (of the status) of a narration (riwaya). A narration (riwaya) does not require the same (acceptance) as definite knowledge (diraya)." The Basran could not find an answer to this and departed.
However, al-Mufid took up the discussion:
"O Shaykh, I have a problem," he said to 'Ali b. 'Isa.
"Put it forward, then," replied the latter.
"What would you say about someone who fought against a just Imam?" asked al-Mufid.
"He is an unbeliever (kafir)," was the answer. Then after a pause he changed it to "grave sinner (fasiq)."
"What do you say about the Commander of the Faithful, 'Ali b. Abi Talib?" . He was an Imam."
"What do you say about the Battle of the Camel, and some of the companions who fought against Ali b. Abi Talib." Therefore according to the above argument they should be described as fasiq, that is grave sinners who would go to hell. (However there is a tradition that these companions were among ten people whom the Prophet said would go to heaven. Thus 'Ali b. 'Isa has to explain how they could be fasiq and go to heaven. He does this in his next answer.)
"The tradition of the Battle of the Camel is definite knowledge (diraya) while the tradition of the repentance is a narration (riwaya)," replied al-Mufid.
Thus al-Mufid had turned the tables on him. The event of the cave was something all Muslims accepted as fact but there was no point in giving the well-reported tradition of Ghadir Khumm inferior status, since if this was done, the same terminology could be used to question the repentance of the said companions, which was also accepted by most Muslims.
'Ali b. 'Isa was very impressed by the young man's reasoning. He asked him about his teacher and then gave him a note to take to that man. In the note he recommended his intellect and gave him the nickname of al-Mufid, "the one who gives benefit".