Objective To evaluate left ventricular systolic function in patients with different degrees of aortic stenosis(AS) by three-dimensional speckle tracking imaging(3D-STI). Methods Sixty-six AS patients with normal left ventricular ejection fraction (LVEF) were divided into mild (25 cases), moderate (21 cases) and severe(20 cases)AS groups.Another 30 normal subjects from regular physical examination were selected as control group. All groups were performed two and three dimensional imaging. Left ventricular ejection fraction (LVEF), global longitudinal strain(GLS), circumferential strain(GCS),area strain(GAS) and radial strain(GRS) were measured with 3D-STI .Results Compared with the control group,GLS in mild AS group decreased(P<0.05), GRS, GCS had no significant difference (P>0.05).Compared with control group and mild AS group, GLS and GRS in moderate AS group decreased (P<0.05), GCS increased (P<0.05). Compared with control group, mild and moderate AS groups, GLS and GRS decreased (P<0.05), GCS increased (P<0.05) in severe AS group. GAS had no significant difference in all groups(P>0.05).GLS, GCS, GAS and GRS were positively correlated with LVEF(r=0.71、0.59、0.79、0.57, P<0.01, respectively).Conclusion The left ventricular myocardial function have already impaired when AS is mild, and the damage is more obvious with the increase of stenosis degree.3D-STI can be used for early evaluation.