Objective To investigate the value ofthree-dimensional strain imaging（3D-STI） inevaluating left ventricular myocardial mechanics in patients withnon-ST-segment elevation myocardial infarction（NSTEMI）. Methods Thirty-eight NSTEMI patients without regional wall motion abnormality（RWMA）from routine ultrasound examinationwere selected as the case group andthirty healthy people matched with age and sex were used as the control.Echocardiography，blood myocardial enzymes examination and blood biochemical testing were performed in all subjects.The left ventricular end-diastolic diameter（LVED），leftventricular fractional shortening （FS），left ventricular ejection fraction（EF） and stroke volume（SV）were measured.And then the global longitudinal peak systolic strain（GLS），global radial peak systolic strain（GRS），global circumferential peak systolic strain（GCS），and global area peak systolic strain（GAS） were obtained from 3D-STI.Results 1.Compared with the control group，GAS in the NSTEMI group was reduced [（-31.27 ± 1.87）% VS （-42.02 ± 1.26）%，t = 17.02，P = 0.000]，and the blood hs-CTnI increased [（2.11 ± 1.78） % VS （0.07 ± 0.01）%，t = 6.25，P = 0.000]，but there were no significant differences in GLS，GRS，GCS ，LVED，LVEF，FS andSV （P> 0.05）.2.There were no significant differences in age，blood pressure，blood lipids，blood glucose，blood creatinine，blood uric acid，blood CK-MB and NT-proBN between the two groups （P> 0.05）.3.Correlation analysis showed that there was a correlation between GAS and LVEF，FS，hs-CTnI （r = 0.45，0.25，0.61，P ＜0.05） while GAS didn’t correlated to LVED，SV，blood CK-MB，NT-proBN ，blood pressure and blood biochemical indicators significantly （P> 0.05）.The ROC curve shows that the sensitivity of evaluating NSTEMI is 92.1 %，the specificity is 80% according to the absolute value of GAS is less than 18.15%，and the area under the curve is 0.91.Conclusion 3D-STI can quantitatively analyze the mechanical characteristics of left ventricular myocardium in NSTEMI，and provide a non-invasive and simple new method for clinical evaluation of NSTEMI.