Methane emission from rice paddy field had been studied for 5 years in Leshan Sichuan province south - west China. Two emission peaks were found during the whole growing season,and these two peaks have a good relationship with the hight changing rate of the rice plant. Organic fertilizer can increase the methane emission rate. Fermented fertilizer from biogas pits can decrease methane emission rate. Hybrid rice paddy has a lower methane emission rate and a higher plants and a higher yield compared with normal rice paddy.The average methane emission rate for 5 year is 67. 0 mg/m². h,which should be regarded as a upper limit.