The photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra under near infrared (800 nm) excitation from porous silicon (PS) prepared by electrochemical anodization method are measured. The results show that PS has efficient infrared-upconversion luminescence, and the peak intensity increased obviously as the reserved time prolonged. This nonlinear optical response enhancement effect is related to the excited local binded exciton interacted by space quantum confined effect. The multipeak in PL spectra show that there are many kinds of different luminescence centers.