Abstract: To investigate the effects of different organic materials on soil amelioration, a field experiment was conducted from 2015 to 2017. The effects of rice straw returning, maize stalk returning, tobacco stalk returning and decomposed organic manure on the nutrient contents, enzyme activities, microbial quantity and functional microbes in tobacco-planting soils were studied. The results showed that straw returning and decomposed organic manure increased the contents of organic carbon, available potassium, zinc, magnesium and boron. Comparing with the control, the activities of invertase, urease and phosphatase were increased by 55.0%, 25.1% and 129.5%, respectively. Especially, decomposed organic manure had an excellent effect. Under the treatments of straw returning and decomposed organic manure, the total amount of OTUs of soil microbes were 8 038- 8 643 and increased by 7.4%-15.5% comparing with the control. Decomposed organic manure promoted the community diversity and abundance of microbes and decreased the relative abundance of nitrogen-fixing microbes. Straw returning decreased the relative abundances of nitrification and denitrification microbes and improved the relative abundance of nitrogen-fixing microbes and their nitrogen-fixing ability. Straw returning and decomposed organic manure reduced the relative abundance of pathogenic bacteria in tobacco-planting soils, decomposed organic manure decreased by 37.9% comparing with the control, and its susceptible risk reducing effect was better than straw returning. In conclusion, the effects of decomposed organic manure were more beneficial to tobacco production than straw returning.