Abstract: To study the effect of straw returning on soil physical and chemical properties and maize yield under different treatments, through a randomized block test in field, the yield of maize was measured after harvest in autumn, and the soil samples were collected by S shape in each experimental plot. The indexes of soil organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium and pH were measured according to the corresponding method in the boratory, and the data of each index and yield were analyzed by variance analysis. The results showed that the content of soil organic matter and total potassium increased significantly with decomposing agent after the straw returned to field, but there was no effect on the content of soil total nitrogen, total phosphorus, available P, available K, and volume weight of soil, pH, and yield of maize. The content of soil organic matter, total nitrogen, total phosphorus, available phosphorus, total potassium and available potassium increased significantly after the film mulching, and the volume weight of soil decreased significantly, however under condition of film mulching with no straw returning, there was no effect on soil total phosphorus. Straw returning significantly increased soil total nitrogen, total phosphorus, total potassium, available phosphorus and available potassium, and significantly reduced the volume weight of soil. The yield of maize increased significantly after straw returning to field. Under the condition of no film mulching, the yield increased by 9.7% compare with that of the control. The film mulching could greatly increase the yield of maize, and the yield increased by 48.8%, and the increasing yield could reach 59.1% with film mulching after the straw returned to field. Therefore, film mulching and straw returning can significantly increase the yield of maize, and the increasing yield with film mulching is higher than that of straw returning. In short, plastic mulching is an important measure for increasing yield in the Loess Plateau and straw returning with film mulching and decomposing agent should be popularized in maize production.