In this research, a new method based on the hyperspectral imaging for searching the best decocting time of sun dried ginseng is reported. The spectral images at different decocting time of test sample have been taken by the staring hyperspectral fluorescence imaging system and the solubility of active ingredients have been discussed by analyzing the changes on the spectral curves. The spectral range of the system is 400–720 nm and the spectral resolution is 5 nm. In the decocting process, the active ingredients of nonsoaked ginseng was dissolved in the tissue fluid at first, and reached equilibrium condition at last after the precipitation–dissolution reciprocating process of boiling. At last, the experimental results show that the best decoction time of sun dried ginseng is about 60 min after boiling.