Abstract: 　Objective　To explore the clinical characteristics and influencing factors of primary nephrotic syndrome (PNS) combined with hypercoagulability in children. Methods　The clinical data of 57 children with primary PNS were analyzed retrospectively. The clinical features and treatment were compared among high coagulation state group, non high coagulation state group and control group (20 children). At the same time, the differences between the simple nephrotic syndrome group (SNS) and nephritic syndrome group (NNS) in hypercoagulable state were analyzed. In addition, the correlation analysis was performed. Results　Among 57 patients, there were 50 patients in high coagulation state group and 7 in non high coagulation state group. There was no significant difference in gender, age and clinical manifestations between two groups (P>0.05). The platelet (PLT) count, platelet aggregation (PCT), albumin (Alb), fibrinogen (Fib), D-dimer (D2) were significantly higher than those in the control group, and there were statistically significant differences (P all<0.01). There were significant differences in the levels of PLT, Fib, D2 and complement C4 between hypercoagulable state group and non hypercoagulable state group (P all<0.05). There were significant differences in HCT, TC, LDL, PT and complement C3 levels between SNS group (n = 32) and NNS group (n = 18) in 50 patients with high coagulation state (P<0.05). There was positive correlation between HCT and complement C3 (r=0.30, P<0.05), while there was no correlation between PLT and other indices (P>0.05). All of the 57 patients were improved and has no thrombosis after the treatment. Conclusion　Children with primary PNS were usually associated with different degrees of hypercoagulable state, and PLT, Fib, D2 could be used as reference indices for the severity of hypercoagulable state, and the activation of complement system might be related to the occurrence and development of hypercoagulable state.