Abstract: Intensive cropping and a high multiple cropping index have been shown to be important for food security in China. However, inappropriate cropping systems decreases soil quality and causes environmental problems. In this study, three legume green manures, Crotalaria junceal, Phaseolus calcaltus and Sesbania cannabina were intercropped with summer corn in a winter canola production area in Chongqing, southwestern China. Soil nutrient availability, plant nutrient content, and aboveground biomass yields were assessed. Corn yield increased 35% when intercropped with C. junceal, reduced by 21% when intercropped with S. cannabina, and was not affected by P. calcaltus. No differences in plant nitrogen and phosphorus were detected apart from S. cannabina which had higher nitrogen when intercropped. Potassium contents were higher under monoculture compared with intercropping for all three intercrop species. Compared with monoculture corn, nitrogen, phosphorus and potassium increased in corn intercropped with green manures. Soil NO₃ nitrogen, available phosphorus and available potassium under intercropped corn were all higher than under monoculture corn. Correlation analysis indicated that nitrogen content was positively correlated with soil NO₃ levels. Among the three legume green crops, S. cannabina had the lowest plant nitrogen content and aboveground yield which negatively influenced corn yield; P. calcaltus had higher aboveground yield and had no effect on corn yield, however its long vines hindered the corn harvest. However, C. junceal had high nitrogen content and high yield, and increased corn yield suggesting that C. junceal might be a suitable legume green manure crop with summer corn.