Silicon nanowires is one of key photoelectric materials. In this paper, silicon nanowires have been fabricated by chemical vapor deposition, the Raman spectra and photoluminescence spectra excited by 532 nm laser have been studied, first-order Raman peaks were found to red shift and broaden with the increase of incident power, photoluminescence blueshifted to shorter wavelength and another peak appeared. The experiment results were analyzed by phonon confinement effect, lattice stress, and nonuniform heating effect of laser, the relation between laser power and Raman shift simulated by Matlab, it was found that the nonuniform heating effect of laser is the main reason for Raman spectra and photoluminescence spectra change with incident power.