Abstract: In order to achieve the intensity in the vector light field applicable not far away from the laser diode when applying diffractive optics to shape the beam of laser diode,Kirchhoff diffractive theory and Fresnel approaching method under nonparaxial condition was adopted to derive out each electromagnetic component's distribution and the MATLAB language was adopted to compute the numerical result.The results show that the diode laser is a mixture of TE mode and TM mode except in some special directions,and the function of computing distribution of each electro-magnetic field is realized.The study should be useful for design and analysis of the diffractive optics for LD laser beam shaping.