Fluxes of methane emission from the year-round flooded paddy field and tillage-cropping systems effects were investigated for two years from 15 May 1995 to 15 May 1997 in field in Southwest China. The results showed that fluxes of methane emission from the year-round flooded paddy field during the rice growing seasons varied from 0.47 mg/m²·h to 171.12 mg/m²·h, and averaged 33.91mg/m²·h. But, it was the most important and the most remarkable that there were 2.51~54.42mg/m²·h of methane emission fluxes, averagely 13.24mg/m²·h during the nonrice growing season from 250 days to 280 days yearly. So, the year-round flooded paddy field with 165.82g/m²·a of methane emission flux was the one of largest methane emission flux in varieties of paddy fields in the world now. The ridge culture (semilate rice) could reduce yearly methane emission fluxes in rice paddy field by 3.36% in 1995 and 33.53% in 1996 compared with the year-round flooded paddy field. The mean fluxes of methane emission in the paddy fields under the ridge culture (rice-wheat) system and under the paddy-upland (rice-wheat) rotation system during the rice growing seasons were lower than those under year round flooded paddy field, and yearly fluxes of methane emission only accounted for 36.7% and 11.96%-34.27% of those under year-round flooded paddy field at the sametime. The ridge culture (rice-wheat) system and the paddy-upland (rice-wheat) system were one of the most effective methods for reducing flux of methane emission from the year-round flooded paddy field in Southwest China.