The coherence of semiconductive material is an important assurance to realize the function of micro component. In order to detect micro bulk defects in silicic materials and MEMS components nondestructively, effectively and accurately, based on Generalized Lorenz-Mie Scattering theory, the scattering light intensity distribution of the interaction between spherical defects and infrared laser beam in non-vertical direction, which aim at the physical property of silicic materials and MEMS components, is studied, and the mathematical simulation by computer is done. A new method to detect micro defect in MEMS components by analyzing back scattering light intensity distribution of infrared laser is presented. The basic principle and theoretic model of the detection is introduced, and the validity and feasibility of the method are proven by experiment.