Abstract: A two-year pot experiment was conducted to study the effects of different organic materials on the biological characteristics and available nutrients of tobacco-planted soil. The results from both years showed that the application of sesame cake increased the contents of soil alkali hydrolyzed N and soil available P significantly. The content of soil available potassium was increased significantly in the biochar treatment. The activities of soil invertase were increased by 12% in the decomposed straw treatment, and the activities of soil urease were increased by 19% in both the sesame cake treatment and the biochar treatment. The activities of catalase were increased by 27% in the biochar treatment compared to the chemical fertilizer treatment. In addition, the content of soil microbial biomass carbon was the highest in the straw treatment (234.52 mg/kg), and the content of soil microbial biomass nitrogen was the highest in the biochar treatment (35.29 mg/kg). Bacteria were the dominant cultivable microbes in the tobacco-planted soil. The application of biochar could significantly increase the number of cultivable bacteria. And the application of decomposed straw significantly increased the number of cultivable fungi and actinomycetes. Therefore, organic materials application could improve the quality of tobacco-planted soil through enhancing soil microbial characteristics and available nutrients.