Abstract: Effects of the depth of straw (maize) return on sucrose content and related enzymes of wheat were studied under field condition, and two different depths (15 cm and 25 cm) of straw return treatment were conducted in this research. The results showed that sucrose content and SPS activity of flag leaf, sucrose content and AI activity of grain were higher with straw (maize) return treatments compared with normal (nonstraw) cultivation condition. And compared with the 25 cm depth of straw return treatment, the above mentioned indices of 15 cm depth treatment condition at early grain filling stage were higher, while dropped more sharply and lower at late grain filling. However, the sucrose content of the top segment of stem was the highest about 7 days after anthesis with 25 cm depth treatment. And 25 cm depth treatment had the highest grain yield by increasing the spike number per hectare.