The period from sprout to jointing is the flourishing period of root system construction of spring maize and straw decomposition in northeast China.Coordinative relation between them significantly affects the accumulation，transformation and absorption of soil nutrients，and is an important factor to ensure the quality of maize seedlings.The purpose of this study was to regulate soil enzyme activity and activate soil nutrients，and the effects of urea and humic acid on soil enzyme activity，soil nutrient content and nutrient absorption of plant were studied to coordinate the nutrient competition between straw decomposition and plant growth through pot experiments.The results showed that the activities of urease，acid phosphatase and sucrase were decreased by 20.8%，16.1% and 9.7%，respectively，in the soil layer of 5～10 cm，and there was little effect on those in the soil layer of 10～15 cm at the stage of maize elongation.Total nitrogen content and dry matter accumulation decreased by 13.3% and 28.6%，respectively.The application of urea or humic acid with straw improved the activity of soil acid phosphatase，decreased sucrase activity，promoted the accumulation of available phosphorus and available potassium in soil，and increased total nitrogen and total phosphorus content of plant.Acid phosphatase activity of soil was further increased by 36.6%，urease and sucrase activity decreased by 11.0% and 39.2%，respectively，the contents of alkali hydrolyzed nitrogen，available phosphorus and available potassium were increased by 15.8%，185.6% and 45.8%，and the contents of total nitrogen and total potassium increased by 42.9% and 25.7%，respectively，by straw with urea and humic acid.There was no significant difference in dry weight of maize in jointing stage.Application of straw with urea and humic acid effectively alleviated the adverse effect of direct straw returning to field on dry matter accumulation of maize seedlings，and increased the accumulation of soil nutrients and the absorption of nitrogen and potassium in plants.