Objective：To investigate the value of two-dimensional speckle tracking imagine（2D-STI）in detecting the early myocardial dysfunction of left ventricular in patients with breast cancer after receiving drug treatment with anthracyclines. Methods：Thirty-two female patients with breast cancer were enrolled in our study. After surgery，all the patients were treated with epirubicin-based chemotherapy，besides，two-dimensional echocardiography was performed within one week before chemotherapy（T0），one week after the end of the third cycle（T1），and one week after the sixth cycle was finished （T2）. Routine echocardiographic parameters including left ventricular end diastolic diameter（LVDd），end systolic diameter（LVDs），interventricular septum thickness at diastole（IVSd），left ventricular posterior wall thickness at diastole（LVPWd），left ventricular ejection fraction（LVEF），mitral valve predilatation and late peak（Em，Am），and mitral annular velocity（e’） were obtained. Two-dimensional images were defined as apical four-chamber，long-axis，two-chamber views，and the papillary muscles and apical left ventricular short-axis from the base. The images were stored for off-linc analysis of 2D speckle-tracking myocardial strain. Global peak longitudinal，circumferential and radial 2D systolic strain（GLS，GCS，GRS）were measured. Another twenty-three healthy female volunteers were collceted as control group. ROC curve was used to evaluate the sensitivity and specificity of each strain parameter to evaluate the early impairment of left ventricular function. Results：①LVDd，LVDs，IVSd，LVPWd，and LVEF showed no significant decrease compared with control group（P＞0.05），while Em/Am，e’，and Em/e’ in T2 were significantly lower than those in T0 and control group，the difference was statistically significant（P＜0.05）. ②GLS in T1 and T2 were significantly lower than those in T0 and control group，the difference was statistically significant（P＜0.05），but there was no statistical significance between T1 and T2（P＞0.05）. The GCS in T2 was significantly lower than that in T0 and contol group（P＜0.05）. The ROC curves showed that GLS as the best predictor. The area under ROC（AUC）of GLS in T1 was 0.832，and its optimal cut-off value was -14.1%，with a sensitivity of 83.4% and specificity of 85.2%，AUC of GLS in T2 was 0.906，and its optimal cut-off value was -13.8%，with a sensitivity of 92.2% and specificity of 83.7%，AUC of GCS in T2 was 0.577，and its optimal cut-off valur wsa -20.5%，with a sensitivity of 63.0% and specificity of 57.4%. Conclusion：GLS was the best indicator of subsequent cardiotoxic events. Therefore，GLS can be used as a sensitive parameter to devaluate subclinical left ventricular myocardial dysfunction in patients with breast cancer after receiving anthracycline therapy.