We considered intensity distribution of light focused by a high numerical aperture lens without spherical aberration through a planar interface between materials of mismatch refractive index.Amplitude distribution of incident light in lateral plane takes a Gaussian form.Intensity distributions in the focal region are numerically evaluated as a function of probe depth.The results show that intensity distributions in the xz plane are not symmetrical about the focal plane,and focus shift increases and full width of half maximum becomes larger when probe depth increases.