The designed imaging system is the device that measures the continuous spectrum in visible light.In the system,the liquid crystal tunable filter (LCTF) is used as the spectrum-dividing component.CMOS is used as the receiver component.The spectral resolution is 0.5 nm.We grind material into powder or chip them only.It keeps the basic shape of the crude drugs because it does not need sublimating and solvents.The experimental result shows:In visible light,this device can distinguish five traditional Chinese medicine according to absorption spectrum curve of crude drugs.The system adopts noncontact measurement.the detection procedure is fast and non-destructive.