Abstract: Studies on the pollen dissemination of Castanea mollisima in the air at the Caiyuan area, Qianan county indicated that blooming date of the plant differed among years, and the pollen concentration varied sharply with it. Pollen concentration in the air was deeply influenced by the air temperature during the blooming and also by the precipitation to the end of peak florescence, but it is little influenced by the sunshine. The correlation coefficient between the yield and the pollen concentration of C. mollissima during the peak florescence was 0.998～0.999. The predicting error of model based on two-year data was 5.7 % in maximum, 1.13% in minimum and less than 4% on average. The yield was predicted two months earlier than the harvest time. Estimating yield of C. mollissima or crops based on pollen concentration is a good predicting method with high precision and little cost, and much ahead in time.