According to the data collected for litter fall from Cunninghamia lanceolata-broadleaved mixed forest and C. lanceolata forest in Wuyishan National Nature Reserve in Fujian, a model of wave-type time series for analyzing the dynamics of litter fall was used to simulate the monthly change in litter fall in the two forests. Result showed that the model could satisfy the actual data. It is suggested that this method can be applied to the study of litter fall dynamics.