Abstract: To enlarge the application scenario of laser voice acquisition system and analyze the influence of targets- material properties on voice acquisition, based on the acquisition process of voice signal from sound source to target, we established a vibration model of targets based on Sewell-Sharp-Cremer model and proposed a calculation method for targets- vibration amplitude. Through Matlab simulation and experiment, the amplitude and voice acquisition results of Fe, Al, plastic and paper were compared. The results show that the amplitudes of 4 targets decay exponentially during 300 Hz~1 000 Hz and go flat above 1 000 Hz. Vibration amplitudes of non-metallic materials are 69nm and 62 nm while those of metal materils are 30 nm and 10 nm. Therefore, metal materials are more appropriate to be the target for voice detection according to their small dynamic range and low frequency sensitivity.