Objective　To investigate the risk factors for syncope in children with orthostatic intolerance (OI). Methods 　The clinical data from 136 children with OI were retrospectively analyzed. The children were divided into syncope group and non-syncope group based on the existence of syncope. Results　Among the 136 children, 77 children (56.62%) had syncope and 59 children (43.38%) did not have syncope. The differences in BMI, prevalence of inducement of prolonged standing, prevalence of accompanied symptoms of blurred vision/ blacking out, cold sweating and pallor, prevalence of the history of motion sickness and blood flow velocity of MCA were statistically significant between two groups (P<0.05). Conclusions　Children with OI who has low BMI, inducement of prolonged standing, accompanied symptoms of blurred vision/ blacking out, cold sweating and pallor, the history of motion sickness, and fast blood flow velocity of MCA, are prone to syncope.