Abstract: The imaging spectrometer based on acoustic-optic tunable filter (AOTF) is a new detector which integrates image, spectrum and polarization information. Because the acousto-optical crystal is the core optical splitter, its performance can affect the acquisition ability of the target information. Therefore, the key point of AOTF imaging spectrometer development is to study the method for improving the diffraction efficiency of acousto-optical crystal. Firstly we introduced the working principle of AOTF imaging spectrometer, derived the acousto-optical crystal diffraction efficiency equation based on coupled wave theory, then analyzed the influencing factors of the AOTF imaging spectrometer on acousto-optical diffraction efficiency by numerical simulation. Finally, through using TracePro software, we simulated and calculated different incident light. The analysis results show that when the AOTF imaging spectrometer works at the wavelength range of 0.4 μm~0.9 μm, in order to make the diffraction efficiency reach the maximum value and the various influence factors reach the optimal values, the transducer length is d=2.5 mm, the tilt angle of grating selects 80 °and the incident light selects o light.