Abstract: An experiment was carried out in the open-top chambers for elucidating the effect of CO2 enrichment on CH4emission from rice. Significant stimulation of CO2 enrichment on CH4 emission was found in the tillering, panicle initiation, booting, grain filling and maturity stages with the CH4 emission increments of 253%, 288%, 273% and 157% ,respectively. The highest flux, 1.91mgCH4·d-1·p-1,occurred in 106 days after transplanting. We propose that the increase in rice root biomass and root exudate might be the major reason for the stimulation of CH4 emission.