This paper carried research on seed rain intensity, seed rain time, the effects of sound seed input density of Castanopsis fargesii population and Castanopsis carlesii population in the Three Gorges Reservoir. The result showed that: (1) the seed production of Castanopsis carlesii and Castanopsis fargesii was low in the studied population, the seed rain was 36.5 seeds • m-2, 22.6 seeds • m-2, and the sound seed input density were 20.5 seeds • m-2, 9.6 seeds • m-2 respectively. (2) infesting and decay were the main causes of seed losing, 43.8% lost in Castanopsis carlesii population and 67.5% lost in Castanopsis fargesii population. (3) the duration of Castanopsis carlesii and Castanopsis fargesii population’s seed rain were 47days and 37 days, but there was a different top time between two populations, the seed rain peak of Castanopsis carlesii population was from middle to late November, with a distinguishable dropping peak, and the seed rain peak of Castanopsis fargesii population was from early to middle November.(4) temperature has significant effect on sound seed input density of Castanopsis carlesii population, temperature and wind speed have significant effect on sound seed input density of Castanopsis fargesii population.