Abstract: This paper proposed a novel method for investigating the characteristics of an electrically tunable liquid crystal(LC) Fabry-Perot(FP) hyperspectral imaging detectors. The device would be used to sequentially choose the specific wavelength in the range of 3 to 5. Based on the method proposed that the directing vector of liquid crystal materials would be changed in an electric field applied over the electrodes of the device, the refractive index of the FP cavity filled by LC film could be changed electrically. Through the thin film matrix equation, we calculated the transmissivity of the infrared light incident upon the photosensitive plane directly, and then obtained the relationship among the transmissivity, the applied voltage signal, and the wavelength value selected. The most key features of the proposal approach was that the device will be composed of main very thin electrically refractive-index parts, which are two FP interferometers connected closely so as to accurately perform the choice of each single wavelength desired in the spectral range by the device developed.