One method of dielectric microsphere assisted laser irradiation followed by chemical etching for fabrication of sub-micro structure arrays on silicon surface with high processing controllability is presented. Three dimensional micro-structure arrays with high quality of periodicity and homogeneity can be fabricated on silicon surface. The formation rules of microstructure depending on microsphere size, etching time, and laser fluence are analyzed systematically. Based on the finite-difference time-domain simulation and the basic theories of silicon crystallization and chemical etching, the microstructure formation mechanism of the microstructures is investigated. By means of testing reflectivity of fabricated silicon samples, the regulation effect of the microstructure arrays fabricated under different processing conditions on the optical performance of the silicon surfaces is verified.