OBJECTIVE To analyze the influential factors of cardioto xicity in patients with positive breast cancer of human epidermal growth factor receptor 2（HER-2）treated by trastuzumab combined with chemotherapy. METHODS From April 2017 to January 2021，200 HER-2 positive breast cancer patients receiving pirarubicin + cyclophosphamide combined with sequential paclitaxel+trastuzumab were collected from our hospital. According to the presence or absence of cardiotoxicity ，the patients were divided into cardiotoxicity group and non-cardiotoxicity group. The clinical data and echocardiographic results of the patients were collected，and the influential factors of cardiotoxicity were analyzed. RESULTS Among 200 patients，43 patients suffered from cardiotoxicity with the incidence of 21.5％. The proportion of patients with cardiotoxicity during pirarubicin+cyclophosphamide therapy accounted for 5.5％（11/200），and the proportion of patients with cardiotoxicity during sequential paclitaxel+trastuzumab therapy accounted for 20.5％（41/200）；the latter was significantly higher than the former （P＜0.01）. At the same time ，the decrease of left ventricular ejection fraction during sequential therapy of paclitaxel and trastuzumab was significantly higher than that during pirarubicin+cyclophosphamide therapy [ 14％（12％，17％）vs. 7％（3％，10％），P＜0.001]. Compared with patients without cardiotoxicity ，the proportion of patients with cardiotoxicity with a history of hyperlipidemia was significantly higher （P＜ 0.01），while the proportion of patients receiving dexrazoxane was significantly lower （P＜0.01）. Results of binary Logistic regression analysis showed that the history of hyperlipidemia [OR ＝3.672，95％ CI（1.499，8.992），P＝0.004] and the use of dextrazoxane [OR ＝0.154，95％ CI（0.072，0.330）， P＜0.001] were associated with the occurrence of cardiotoxicity. CONCLUSIONS Hyperlipidemia is an independent risk factor for cardiotoxicity induced by pirarubicin + cyclophosphamide combined with sequential paclitaxel+trastuzumab in HER 2 positive breast cancer patients ，while the use of dextrazoxane is a protective factor.