In this paper, the method of extracting and purifying nicotine from waste tobacco leaves was studied, and the 

conditions most favorable for industrial applications were discussed. 

On this basis, the nicotine solution was tested for insecticidal activity and antibacterial activity. The research process of the new biological pesticide was systematically expounded. The experiment used nicotine and capsaicin as the two active ingredients to be compounded according to 11.3:1. The compounding agent has remarkable pharmacological effects. In the research of nicotine extraction process, extraction and extraction were carried out by leaching-extraction-distillation method, and purification was carried out by steam distillation. The nicotine test used common ultraviolet spectrophotometry. The results showed that: organic solvent, dip The time, temperature and stirring have a great influence on the leaching rate of nicotine. The optimum extraction conditions are as follows: at 60 ° C, extraction with 95% ethanol for 6 h. At the same time, higher alkali concentration conditions help to improve nicotine leaching rate and steam distillation efficiency. In the virulence determination, the contact toxicity of nicotine was determined by micro-spray method using potato ladybug as test insect. The results showed that nicotine had good contact activity. The linear interpolation method calculated 48hLC_(50) to be 3.07g╱L, concentration. The 4.4 g/L nicotine agent was equivalent to the 2,500-fold potency of beta-cypermethrin, with corrected mortality rates of 78.9% and 84.2%, respectively. Capsaicin also has a strong contact activity, with a LC_(50) of 1.82 g/L at 48 h. The gastric toxicity was determined by the leaf poisoning method, and the nicotine 48h stomach toxicity LC_(50) was 1.66g/L. Capsaicin is difficult to measure its stomach toxicity activity because of its strong antifeedant and avoidance activity. According to the different concentrations of nicotine and capsaicin, the contact activity was determined, and the optimal ratio was 11.3:1. The ratio has good contact activity and repellent activity, and the drug effect is remarkable.