Located at No. 13, Dongsi Nandajie, the Dongsi Mosque was first constructed in the Ming Dynasty (1368-1644). It has been restored and renovated many times. In 1952 and in 1974, funds were provided by the government to restore the mosque as a center for both Chinese and foreign Muslims in Beijing. It is now the headquarters of the Beijing branch of the Chinese Islamic Association.

The Mosque is formed around three Chinese-style courtyards, with ablution rooms, a library and a prayer hall at the rear. The Prayer Hall is the only survival from the Ming Dynasty and has now been restored to its original splendor after many years of neglect. In front is a paved courtyard planted with gingko trees and flowering shrubs. At one end of the hall verandah is a bell which used to top the minaret (no longer in existence); at the other end of the verandah is a stele with an inscription from the Wanli period (1573-1620) of the Ming Dynasty. The vestibule of the hall is wooden structure in Chinese style. At the rear of the hall are three brick chambers with vaulted ceilings without supporting pillars in Arabic styles; the floor is painted red and carpeted. The mihrab, which should be in the central chamber, is missing. The inner hall is large and grand; the pillars are gilded with a lotus and arabesque design and the beams are painted. In the center of the hall hangs a horizontal board with saying from the Qur' an inscribed in Arabic. The polished wooden floor is covered with rows of prayers mats, which can accommodate 500 people on important occasions such as Eid al-Fitr (the breaking of Ramadan) and Eid al-Adha (also known as Qurban or Corban). Marriage and funeral services are also held here, and Chinese and foreign Muslims in Beijing may come for daily or weekly services. There is a separate area in the main hall for women.

The library houses valuable manuscripts of the Qur' an, the Hadith, a collection of short narratives expounding the sunna (tradition) of the prophet, and Islamic law, transcribed by imams in different periods in Chinese history, works of Islamic philosophy, history and literature, and Islamic classics and other works published in Egypt, India, Turkey and Pakistan. Most of the manuscripts are approximately two or three hundred years old; one particularly valuable manuscript of the Qur'an is about 700 years old.