Stimulated phototuminescence (PL) emission has been observed from an oxide structure of silicon when optically excited by a radiation of 514nm laser.Sharp twin peaks at 694 and 692nm are dominated by stimulated emission,which can be demonstrated by its threshold behaviour and linear transition of emission intensity as a function of pump power.The oxide structure is formed by laser irradiation on silicon and its annealing treatment.A model for explaining the stimulated emission is proposed,in which the trap states of the interface between an oxide of silicon and porous nanocrystal play an important role.