Abstract: Objective To explore the risk factors of capillary leakage syndrome in patients with acute organophosphorus pesticide poisoning (AOPP)， in order to provide reference for clinical screening and intervention timing. Methods The clinical manifestations， auxiliary examination and prognosis of AOPP patients admitted in Fuyang People's Hospital from November 2020 to June 2022 were prospectively analyzed， and the patients were divided into non-CLS group and CLS group according to capillary leak syndrome (CLS). Patients were admitted to hospital as the starting point， and death or discharge as the end point. Multiple Logistic regression analysis was used to explore the risk factors of AOPP complicated with CLS. Results A total of 38 AOPP patients were included， of which 17 (44.7%) were complicated with CLS. There were statistical differences in age (P=0.015)， blood concentration of dichlorvos (P=0.001)， blood concentration of dipterex (P＜0.001)， creatinine (P＜0.001) and APACHEⅡ score (P＜0.001) between nonCLS group and CLS group. Multivariate Logistic regression analysis showed that blood concentration of dipterex ≥0.44μg/mL and APACHEⅡ score ≥10.5 were independent risk factors for AOPP complicated with CLS. The severity of non-CLS patients was much lower than that of CLS group (P＜0.001)， and the cure rate was higher than that of CLS group (P＜0.001). Conclusions Patients with AOPP are more likely to be complicated by CLS， and the mortality of patients with CLS is significantly increased. Blood concentration of trichlorfon ≥0.44μg/mL and APACHEⅡ score ≥10.5 were independent risk factors for CLS. Active treatment of primary disease and reasonable fluid replenishment are the key to treatment.