Objective To explore the value of left ventricular(LV) myocardial work, an innovative parameters of two-dimensional speckle tracking imaging (2D-STI) technique, for assessment of the cardiotoxicity of anthracycline in breast cancer patients.Methods From December 2018 to September 2019,40 patients were selected as the chemotherapy group, who were receiving initial chemotherapy for breast cancer in Northern Jiangsu People′s Hospital, and 20 healthy subjects were selected as the control group. The left ventricular global longitudinal strain (GLS) and myocardial work parameters were measured using 2D-STI. The two groups were compared before the chemotherapy, at 2 cycles and 4 cycles of the chemotherapy respectively. SPSS statistics 25.0 was used for data analysis, and the correlation between variables was analyzed using Spearman correlation. Results No changes were observed in any of the myocardial work parameters after two cycles of therapy and between the two groups (P>0.05). GLS, global work index (GWI) and global constructive work(GCW) in the chemotherapy group decreased at four cycles of anthracycline therapy and were lower than those in the control group(P<0.05). GWI, GCW, global wasted work (GWW), global work efficiency (GWE) were all linearly correlated with GLS (r=-0.873, -0.750,0.582, -0.739; P<0.001 for all). Conclusion LV myocardial work can be used to assess the LV systolic function in breast cancer patients receiving chemotherapy. GWI and GCW are clinically valuable for early monitoring the subclinical LV systolic dysfunction in the breast cancer patients as a result of anthracycline chemotherapy.