Abstract: To provide a theoretical reference for the development of yield prediction of single cropping rice and improve the ability of meteorological services for grain production, based on the data of field experiment and meteorological observation data in Huzhou of Zhejiang, the authors analyzed the characteristics of LAI for single cropping late Japonica Rice (type c-9904) and its relationship with meteorological conditions, by comparative analysis and regression analysis method. The results showed that: (1) Combined with the observation data of leaf area meter，the correction coefficient for measuring leaf area by length width method was 0.70, which was 0.13 smaller than that in “agricultural meteorological observation standard”; (2) The change characteristics of LAI was in line with the process of rice growth, before booting, LAI increased with “S” curve tendency, and then, it decreased gradually; (3) The condition of high temperature and sufficient sunlight was propitious to the rapid growth of LAI, while the shortage of sunlight would slow down its growth; (4) Heavy rains led LAI to increase slowly, rainy days would led LAI to change slowly, however, sunny days would contribute to its rapid growth.