It is based on the different setting velocities of barley and impurities. The washing machine can separate impurities including Bingjian Stone in the similar size with barley so that the de-stoning procedure is omitted. Therefore, the cost is reduced. The environmental dust is controlled efficiently in the process of de-impurity process so that the working environment is improved. Meanwhile, during the cleaning process, the barley has received water's pre-soap which will contribute to the germination effect.