Green manure crops are mainly used to reduce the application of chemical fertilizers. Mixture of green manure crops have beneficial effects in agroecosystem. In this study, experiments were conducted to evaluate the effects of monoculture and mixtures of crimson clover (Trifolium incarnatum) on rice growth and yield in paddy. This experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts) from Oct. 2007 to Oct. 2009 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Seeding rates of crimson clover (CC) were consisted of monoculture (CC2, 3, 4 kg and hairy vetch 5 kg $10a^{-1}$) and mixtures (CC 2 + barley 7, CC 3 + barley 7, CC 4 + barley 7, and CC2 + hairy vetch $5kg;10a^{-1}$). Seeds were drilled by partial tillage machine on 9th Oct. in 2007. Monoculture and mixture of crimson clover as a green manure crop was incorporated in soil for rice cultivation on 15th May in 2008. Chemical fertilizers had not been applied to monoculture and mixture plots. The biomass and N production of monoculture plots were lower than mixture plots. The biomass and N production of CC 2 + hairy vetch $5kg;10a^{-1}$ plot were the highest among mixtures treatments. In rice growing season, ammonium nitrogen concentrations in soil were a little high trends at CC 2 + hairy vetch $5kg;10a^{-1}$ plot. And soil bulk density and porosity were improved at mixture plot after rice harvesting. The rice yield of CC 2 + hairy vetch $5kg;10a^{-1}$ plot was not significantly different from conventional practice plot. These results indicated that cropping of crimson clover with hairy vetch mixture was better than barley mixture for environmental friendly rice cultivation.