GaP crystal is an excellent material for developing acousto-optic modulators (AOMs) because it pos sesses a high acousto-optic (AO) figure of merit, outstanding sound velocity, and a low acoustic attenuation coeffi cient. In this study, important GaP crystal AO parameters were tested and evaluated. A high-speed fiber AOM with an optical pulse rise time of 6.6 ns, a high-frequency AOM with shift frequency of 1.5 GHz, and a large-band width fiber AOM with 3 dB shift bandwidth of 125 MHz based on GaP crystal were developed.