Percolation is a method of continuously adding leaching solvent to the crude powder of medicinal materials to make it penetrate the powder and the leaching liquid flows out from the lower outlet. During percolation, the solvent penetrates into the medicinal material layer. The percolation method is that the leaching solvent is continuously added to the medicinal material layer from top to bottom to dissolve a large amount of soluble substances in the medicinal material layer. After the concentration and density increase, it moves downward and replaces the position with the leaching solvent or dilute leaching liquid in the upper layer, creating a good concentration difference and making the diffusion better and more natural. Therefore, the leaching effect is better than the immersion method and the extraction is more complete.