Purpose To evaluate left ventricular systolic function of patients with obstructive sleep apnea syndrome (OSAS).Materials and Methods Sixty OSAS patients were divided into 16 cases in mild OSAS group,18 cases in medium OSAS group and 26 cases in severe OSAS group in line with polysomnography results.20 healthy people were in the control group.Two-dimensional speckle tracking imaging was adopted to measure left ventricular global longitudinal strain (GLS),global radial strain (GRS),global circumferential strain (GCS),Endo-LS,Mid-LS and Epi-LS of left ventricular long axial section and EndoCS,Mid-CS and Epi-CS of short axial section in OSAS group and control group.Results ① There was no obvious change of GLS and GCS in mild OSAS group and compared with those in control group (P＞0.05),GRS was increased (P＜0.05).GLS,GRS and GCS in medium OSAS group was decreased when compared with those in control group,and the difference was of statistical significance (P＜0.05).GLS in severe OSAS group was reduced compared with that in control group,mild and medium OSAS group and GRS and GCS were also reduced compared with that in control group and mild OSAS group.The difference was of statistical significance (P＜0.05).② OSAS group was represented by Endo-LS reduction and as OSAS worsened,Endo-LS reduced section was enhanced.③ Starting from medium OSAS group,myocardial circumference strain began to decrease,which was represented by Endo-CS and Mid-CS reduction.Conclusion Adoption of two-dimensional speckle tracking imaging for left ventricular global and layered myocardial strain could figure out early stage left ventricular systolic function disorder in OSAS patients,providing more valuable information for clinical activities and guidance of early intervention for OSAS patients.