Fluxes of methane emission from the year - round flooded paddy field andtillage-cropping systems effects were investigared for two yeare from 15 May 1995to 15 May 1997 in field in Southwest China The results showed that fluxes ofmethane emission from the yeare-round flood paddy field during the rice growingseasons varied from 0.47 mg/m2. h to 171.12 mg/m2·h, and averaged 33.91mg/m2·h.But it was the most impothet and the m0st remarkable that there were 2.51～54.42mg /m2. h of methane endssion fluxes, averagely 13.24mg / m2·h during thenonrice growing season from 250 days to 280 days yeary. So, the year- roundflooded paddy field with 165.82g / m2·a of methane emission flux was the one oflargest methane emission flux in varieties of paddy fields in the worid now. Theridge culture (sendlate rice) could reduce yeary methane endssion fluxes in ricepaddy field by 3.36% in 1995 and 33.53% in 1996 compared with the year-roundflooded paddy field. The mean fluxes of methan emission in the paddy fields underthe ridge culture (rice-wheat) system and undr the paddy-upland (rice-wheat)rotation system during the rice growing seasons were lower than those under year-round flooded paddy field, and yeary fluxes of methane emission only accounted for36.7% and 11.96%~ 34.27% of those undr year-round flooded paddy field at thesametime.The ridge culture (rice-wheat) system and the paddy-upland (rice-wheat)system were one of the most effective methods for reducing flux of methan emissionfrom the yeareround flooded paddy field in sonthwest China