Abstract: Objective To observe efficacy difference of unfractionated heparin versus low molecular weight heparin sodium in preventing venous thromboembolism(VTE)in lung cancer patients. Methods A total of 96 lung cancer patients were enrolled, and were divided into two groups by random number table method. The experimental group(n=48)was treated with low molecular weight heparin sodium to prevent VTE, while the control group(n=48)was treated with unfractionated heparin to prevent VTE. The incidence of VTE, coagulation function indexes and blood platelet count(PLT), blood gas indexes of pulmonary artery, occurrence of adverse reactions and quality of life scores were compared between the two groups. Results After treatment, incidence of VTE in experimental group was lower than that in control group(4.17% vs. 16.67%, P<0.05). There were no significant differences in PLT, fibrinogen(FIB), prothrombin time(PT)or activated partial thromboplastin time(APTT)between the two groups before and after treatment(P>0.05). After treatment, partial pressure of carbon dioxide ［p(CO₂)］, blood oxygen partial pressure ［p(O₂)］ and arterial oxygen saturation(SaO₂)in the experimental group were higher than those in control group(P<0.05), and the experimental group was better than the control group(P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05). At discharge, quality of life in both groups was higher than that before treatment(P<0.05). There was no difference in quality of life between the two groups at discharge(P>0.05). Conclusion Compared - with unfractionated heparin, low molecular weight heparin sodium has significant efficacy in preventing VTE in lung cancer patients and can promote the survival quality, with less effects on blood gas indexes, coagulation function indexes and blood platelet.