Objective: To investigate the incidence and classification of cardiac toxicity in patients with HER2 positive breast cancer who treated with trastuzumab. Methods: The relevant literature were searched in PubMed, EMBASE, Web of Science and Cochrane library until December, 2016. Phase III RCTs were included according to inclusion criteria for screening and assessment of the literature ultimately. As the system evaluation method of Cochrane Handbook 5.1.0, the literature was screened, data were extracted and checked by 2 reviewers respectively. Meta-analysis was then performed using R software to compare the treatment of trastuzumab and traditional treatment on cardiotoxicity in patients with breast cancer. Results expressed as the relative risk (RR) and 95% confidence interval (CI). Results: A total of 6 RCTs involving 18 622 patients were finally included, of which 11 766 cases in trastuzumab group, and 6 856 cases in the control group. Compared with the control group, Meta-analysis showed the occurrence of cardiac toxicity events which above grade II increased significantly in experience group (RR=3.56, 95%CI 1.52–8.33, P<0.001). While the incidence of grade III–IV was higher(RR=2.89, 95%CI 1.77–4.71, P<0.001). However, differences in the aspect of cardiac death had no significance. Subgroup analysis shows that the cardiotoxicity of grade II by trastuzumab in Europe was higher than that of the United states. But there was no difference between the group that contains paclitaxel and/or anthracyclines and the group of without paclitaxel and anthracycline. Conclusion: This pooled analysis suggests that trastuzumab for patients with HER2 overexpress breast cancer is associate with increased risk of adverse cardiac events upon grade II, III. Nevertheless ,there is no significant difference in the occurrence of cardiac death.