Acousto-Optic Tunable Filter ( AOTF) is a dispersive element based on acousto-optic effect. By chan- ging the ultrasonic frequency ,the diffraction direction of the light can be changed ,so as to select the wavelength. In this study ,a new two-pass dispersive AOTF structure is designed and studied using finite element analysis software. The results of the present study show that the design of this dual-range dispersive AOTF can effectively compress the spectral linewidth. When the center wavelength is 1 064 nm ,the linewidth compression efficiency reaches 28. 6% at an ultrasonic operating frequency of 84 MHz ,which indicates that the spectral resolution has been significantly im- proved ; at the same time ,this structure also has a strong inhibition of sidelobes ,which can compress the sidelobes of the diffracted light with a center wavelength of 1 064 nm from -27. 0 dB to -44. 8 dB ,which improves the spectral pu- rity.