Objective To analyze the clinical characters and identify the risk factors in patients diagnosed with systemic lupus erythematosus (SLE) and thrombotic thrombocytopenic purpura (TTP). Methods We retrospectively analyze the clinical features, laboratorial test results and treatment strategy of 20 SLE patients with TTP diagnosed in the First Affiliated Hospital of Zhengzhou University from 2011 to 2018. Multiple logistic regression model was used to determine risk factors for TTP. Results Among 20 SLE with TTP patients, 16 were female and 4 were male. The median age at diagnosis was 47 (14-74) years old. Three cases of TTP were diagnosed during the treatment of SLE, 16 cases were diagnosed after the diagnosis of SLE, while 1 case was diagnosed before SLE. Logistic analysis showed that the independent risk factors for TTP included Systemiclupus erythematosus disease activity index (SLEDAI)>10, renal and CNS involvement (P<0.05). Conclusion Patients with SLE who have moderate or high disease activity, renal and Central nervous system (CNS) involvement significantly increases the risk of TTP.