Abstract: To analyze focalization character of Gaussian beams passing through optical system with misaligned lens，an approximate expanded formula of misaligned circular aperture function and an generalized diffraction formula were used. The dependence of field distribution of output beam maximum value on the landscape orientation displacement and angle displacement were given. Result shows that various misaligned components have effects on the field distribution of reflection beam. Based on a specific lens system, the impact of maladjustment factors on output beams maximum value field distribution was analyzed quantitatively. The results show that the transverse-displacement has more impact than the angle-displacement on the focalization character when the parameter is small.