Objective To evaluate the changes of the left ventriclar systolic function after PCI in patients with acute coronary syndrome by stratified strain technique. Methods Acute onset and the first diagnosis of ACS and received elective or emergency PCI treatment of patients with 44 cases, 40 cases of normal physical examination as a control group; The apical four-chamber, two-chamber, three-chamber incision and mitral, papillary muscle and apical short-axis dynamic images were used for five consecutive cardiac cycles. Echo PAC workstation and analysis software were used to obtain the longitudinal strain (GLSendo, GLSepi, TLSendo, TLSmidi, TLSepi) of the left ventricular septum in the subendocardial, middle and epicardium. According to the results of coronary angiography, the affected segments were screened and the longitudinal strain of the subendocardial, middle and epicardium were obtained. And analyze the differences between the corresponding parameters. Results Compared with the control group, The whole and segment longitudinal strain of the patients with ACS were significantly lower (P <0.05); Compared with preoperative, the longitudinal strain of the left ventricular septum and the affected segment were improved after operation, and the improvement was significant at 3 months and 6 months (P <0.05). The strain parameters were slightly higher at 1 week postoperatively, but the difference was not statistically significant (P> 0.05) Conclusion The left ventricular systolic function is reduced in patients with ACS, and the myocardial systolic function of the left ventricle is improved after PCI ,endocardial myocardium strain recovery faster than epicardial myocardium.The strain parameters obtained by stratified strain technique can accurately evaluate the local and total systolic function of left ventricle before and after PCI in patients with ACS, which can effectively evaluate the therapeutic effect of PCI.