Abstract:Pollen dispersal from rice results in gene flows. The transgenic flow from transgenic rice can be risky for environmental safety. In order to investigate the pollen disposal processes, field experiments with a hybrid rice (Oryza sativa L. cv. indica) were conducted in Nanjing (32 01′N，118°52′E) and Lishui, (31°35′N，119°11′E) Jiangsu, China in 2007 and 2009. The concentration of pollen grain in the air was measured and the gradient data of the environment factors were obtained from a meteorological tower. A model for simulating rice pollen dispersal was developed based on the Gaussian plume model. Least square regression was used to estimate the mean pollen grain release rate. Independent experimental data were used to validate the model. The results showed that the peak of pollen release in the filed scale occurred from 09:00 to 11:00 during 1-5 day after anthesis. The amount of pollen releasing was significantly dependent on the flowering number (r＝0.880**). The simulated rice pollen concentration agreed well with the measured one. The root mean square error and the relative error between the simulated and the measured values were, respectively, 0.509 grain/(m2?d) and 3.47%. The results indicate that this pollen dispersal model can properly simulate pollen distribution in the air. Improvements, however, are needed for the model to predict the concentration of pollen grain, especially at the larger scale field.