SRS2, a preparation for resistance induction in tobacco, was made from cell wall components of Alternaria alternata spores and combined with the chemical ID1 as a resistance inducer. In greenhouse experiments, SRS2 induced over 50% resistance and nearly 100% protection of the plants from brown spot. Tests were carried out in five fields in Shandong and Anhui provinces, where the fungicide dimethachlon was applied as a control. SRS2 had three functions in the fields. In most observation sets, it decreased disease severity by over 75%, which was 15-30% higher than with dimethachlon. Analysis of chemical compounds indicated the roles of SRS2 in improving quality of cured leaves, which had 1,0-2,9 K:CL and 4,5-6,8 sugar:nicotine ratios. The function of SRS2 in improving quality was proved to be due to the cell was components of the fungal spore. Effects of the preparation in improving agronomic and economic properties of tobacco were also shown. In fields where SRS2 was applied, yield and value of cured leaves were increased by 7-110% and 79-136%, which were better than those achieved in the fields that were treated with dimethachlon.