During the period of processing of longjing tea in the Reciprocation-trough type machine, the change of moisture content possessed an equal rate and a reducing rate. Because the trough movement is a standard crank mechanism, the movement equation on the displacement(s), speed(v), acceleration(a) and time(t) was established. Regarding the tea leaf as particle, the size of receiving force of tea leaf could be calculated. The tea leaves formed straight shape under the acting of strike force in reciprocation tough and formed flat shape under the pressing of weight pole.