To systematically review the efficacy and safety of low molecular weight heparin (LMWH) in treating patients with lung cancer received chemotherapy. Databases including PubMed, The Cochrane Library, Excerpt Medica Database, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP, and Wanfang Data were searched for the randomized controlled trials (RCTs) about LMWH in treating patients with lung cancer received chemotherapy from the establishment to May 31, 2015. According to the inclusion and exclusion criteria, two reviewers independently screened literature, extracted data, and assessed quality of the included studies. Meta-analysis was then performed by using Review Manager 5.3 (Cochrane Collaboration, Oxford, UK) software. A total of eight RCTs involving 952 patients were finally included. Meta-analysis showed that compared with the control group, LMWH significantly improved the 1- and 2-year overall survival (OS) rates of the patients with lung cancer received chemotherapy (risk ratio [RR] =1.65, 95% confidence interval [95% CI] [1.20-2.26], P = 0.002; RR = 2.63, 95% CI [1.40-4.94], P = 0.003, respectively), and significantly reduced the incidence of venous thromboembolism (VTE) (RR = 0.40, 95% CI [0.23-0.69], P = 0.001), not significantly increased the incidence of major bleeding events and thrombocytopenia (RR = 1.29, 95% CI [0.57-2.96], P = 0.54; RR = 0.86, 95% CI [0.69-1.07], P = 0.18, respectively), and not significantly improved the overall response rate (RR = 1.24, 95% CI [0.98-1.57], P = 0.07). LMWH improves the 1- and 2-year OS rates of the patients with lung cancer received chemotherapy and reduces the incidence of VTE, not increase the incidence of major bleeding events and thrombocytopenia. These show that there is a certain effect of LMWH, and the security is good.