LC-based tunable filter with large aperture has been developed utilizing the effect of electric controlled birefringence. Spectral test indicated that this filter can operate in the visible band with an average 20 nm FWHM. A small scale spectral imaging system was established based on this tunable filter. Spectral imaging experiments on a certain number of samples show that this system can be tuned continuously with random-access selection of any wavelength, and has a higher level of resolving power in respect of both imaging and spectral tuning in the visible band, which has a brilliant application potentiality in biology, iatrology, environmental protection, resource detection through hyper-spectral imaging or ultra-spectral imaging.