OBJECTIVE To explore the clinical characteristics and influencing factors of immune-related adverse events （irAEs） in patients with extensive-stage small cell lung cancer （SCLC） treated with immune checkpoint inhibitors （ICIs）. METHODS The data from 130 patients with extensive-stage SCLC treated with ICIs at our hospital from January 1， 2023， to May 31， 2023 was collected retrospectively using the Chinese Hospital Pharmacovigilance System. The occurrence of irAEs and the use of corticosteroids during treatment for all patients were recorded. A multifactorial Logistic regression model was used to analyze the influencing factors for the occurrence of irAEs. RESULTS Among the 130 patients included， 32 patients experienced 38 episodes of irAEs， with an incidence rate of 24.6% and severity of degree 1-3. Skin symptoms were the most common （8.4%） and predominantly occurred in the first cycle of treatment. Five patients developed irAEs involving multiple organ systems. The irrational use rate of corticosteroids in patients with irAEs was 23.1% （excluding patients with thyroid dysfunction）. Neuron specific enolase （NSE） was a independent factor influencing the occurrence of irAEs （P＜0.05）. CONCLUSIONS The incidence of irAEs caused by ICIs remains relatively high and can involve various organ systems throughout the body， with skin symptoms occurring earliest. NSE is an independent influencing factor for the occurrence of irAEs， and could predict the risk of irAEs to a certain extent.