Microwave-assisted extraction of nicotine from discarded tobacco leaves was optimized through orthogonal experiment. The effects of soaking time, ratios of solid to liquid, microwaving power, microwaving time on the extraction yield of nicotine were investigated. The results showed that the optimum microwaving power for nicotine extraction through microwave-assisted method was 800 W, the optimum microwaving time was 7 min, the optimum soaking time was 4 h, and the optimum ratios of solid to liquid is 1∶7. Under these conditions the extraction rate of nicotine was up to 98.68 %.