Abstract: The incidence of the opportunistic infection of pneumocystis carini pneumonia(PCP) in patients with autoimmune diseases has increased over recent years, because of the use of glucocorticoids, immunosuppressants, small molecule targeted drugs and biological agents. This group of patients show more rapid progress and higher mortality than human immunodeficiency virus positive patients with PCP. Sulfonamide is the first-line treatment for PCP. Many scholars advocate taking trimethoprim-sulfamethoxazole(TMP-SMZ) for prophylaxis of PCP. However, the adverse effects of sulfonamides and drug resistance cannot be ignored. This article reviews the risk factors for the development of PCP in patients with autoimmune diseases, the effectiveness of PCP prevention with TMP-SMZ, and adverse drug reactions, tolerance, and drug resistance.