Abstract: In order to resolve the problems of slow straw decomposition, crop pests and lack of nitrogen during the straw returning, indoor soil columns experiments were conducted and effects of the soil decomposition rates of powdered straw with different C/N ratios on soil bulk density, soil water holding capacity were analyzed. The results showed that the powdered size of straw had little effect on its decomposition rate in the short term, while the decomposition rate of powdered straw was significantly higher than that of long straw at the later stage. Thus ammoniation could significantly speed up the decomposition rate of straw. Powdered straw decreased soil bulk density more significantly than long straw. Throughout the whole experiment, the soil bulk density of straw treated with powdered and ammoniated straw was significantly lower than that of other treatment after the same incubation. The water-holding capacity of all the straw utilization treatments has little difference, however the powdered and ammoniated straw could significantly increase soil drought tolerance. This research can provide a theoretical basis for exploring a new way of straw returning to get the maximum benefit in soil improvement.