In order to investigate the effects of water and nitrogen conditions on maize yield and soil carbon and nitrogen,the experiment was carried out in 2018 in maize and autumn maize growing season in the maize growing region of Guangxi.The variety is Wanchuan 1306,the planting density is 52,500 plants/ha,row spacing was 60 cm,and the plot area is 16.8 m².Split plot design was used in the experiment.The main treatment water conditionswere rain-fed and irrigation,and the nitrogen application rates were 0 kg/ha （N₀）,150 kg/ha （N₁）,200 kg/ha （N₂）,250 kg/ha （N₃）,300 kg/ha （N₄）.Soil organic carbon,soil microbial biomass carbon and soil organic nitrogen components were measured in soil surface layer （0-20 cm） at maize maturity stage.The result showed that the order of soilorganic nitrogen was amino acid nitrogen≈ammonia nitrogen＞acid hydrolysis unknown nitrogen＞amino sugar nitrogen.In spring maize,the yield of irrigation combined with N₃reached the highest value,which was 7,806 kg/ha,and in autumn maize,the yield of irrigation and rain-fed was basically the same.There was a significant positive correlation between nitrogen application rate and crop yield （P＜0.01）,but excessive nitrogen application could not significantly increase crop yield.Soil microbial biomass carbon was positively correlated with crop yield （P＜0.01）.Under the condition of periodic drought,spring maize in Guangxi had better soil potential of carbon and nitrogen sup-ply and higher yield with proper water supply and nitrogen application rate of 250 kg/ha.