In the present paper, using designed liquid crystal spectral imaging device, the transmission spectra of leaves of uncaria were detected and analysed under different environmental situations. The characteristic curve was drawn and the imaging characteristic spectrum was constructed and cluster analysis was performed. The results showed the similarity of imaging characteristic spectrum of uncaria leaves and the results of determining genetic relationship in cluster analysis were consistent with the results of the identification of plant taxonomy. Spectral imaging analysis techniques can be applied to discuss the genetic relationship of uncaria. The liquid crystal spectral imaging system can detect traditional Chinese medicine rapidly and nondestructively. The same sample can be used to repeat several experiments. Experimental operation is simple and quick. It can provide a new detection method for Chinese medicine.