OBJECTIVE： To observe the safety and therapeutic efficacy of low molecular weight heparin calcium in the prevention of venous thromboembolism （VTE） of ICU patients. METHODS： 572 VTE patients were randomly divided into trial group and control group， with 286 cases in each group. Trial group was given Low molecular weight heparin calcium injection 0.3-0.6 ml，im，qd； control group was given Rivaroxaban tablet 10 mg， po， qd. The incidence of VTE， platelet count， coagulation function， quality score of life and the occurrence of ADR were compared between 2 groups. RESULTS： The incidence of VTE in trial group （0.3％） was significantly lower than control group （2.1％）， with statistical significance （P＜0.05）. There was no statistical significance in platelet count， prothrombin time， APPT，  fibrinogen and other indexes between 2 groups before and after treatment （P＞0.05）. The physical health， body function and role， general health， emotional role function， mental health and other aspects of trial group were improved significantly， compared to control group， with statistical significance （P＞0.05）. No obvious ADR was found in 2 groups. CONCLUSIONS： Low molecular weight heparin calcium can effectively prevent VTE and improve the quality of life， while doesn’t influence platelet count and coagulation function with good safety.