Spectral resolution is the key of acousto-optic tunable filter (AOTF). Based on the working principle of acousto-optic filter, a hyperspectral imaging system based on double-filter structure is designed by connecting two filters in series. By comparing the theoretical calculation and experimental measurement results of single filter and double filter, it can be found that the spectral width of double filter structure is smaller than that of single filter when the center wavelength is equal, which shows that the double filter technology can improve the spectral width. In addition, the microscopic imaging system based on double-filter technology is designed by using dual-filter structure combined with inverted light microscope. Based on a large number of microscopic images of gastric cancer tissue hyperspectral images, three spectral images with a small correlation coefficient are selected and processed using RGB false color image fusion technology. The simulation results show that the hyperspectral image fusion technology can effectively improve the image quality.