Abstract: In order to obtain the multispectral image of the test sample non destructively, a method of obtaining the multispectral image by using the liquid crystal tunable filter (LCTF) is studied. LCTF has the functions of light modulation, deflection and filtering. The cascade of multi-stage Lyot wave plates can be electronically tuned in a wide spectral band. By changing the applied voltage, the dynamic modulation of the filter can be realized to obtain high-precision narrow-band spectral output. Compared with the traditional multi spectral image acquisition using multi spectral spectrometer, LCTF has the advantages of simple control, low modulation voltage, fast continuous modulation and so on. In this paper, the voltage phase delay characteristics of a group of wave plates are measured by 1/4 wave plate method, and the appropriate wave plates are selected to form a triple filter to realize the narrow-band filtering of broadband spectrum. Based on the multispectral imaging device obtained by this method, the method of non-destructive testing for fruit quality is studied.