An experiment on degradation of nicotine in tobacco leaves by enzymes was conducted in order to develop an effective method for reducing nicotine content in tobacco leaves. A polyenzyme system was obtained by treating selected tobacco microorganism after its cell wall was broken in supercritical carbon dioxide. The tobacco leaves were sprayed with the enzymes at different dosages and panel evaluated at different intervals along with nicotine determination. The results indicated that: 1) the nicotine in the treated tobaccos decreased at a rate tens to hundreds times faster than that in natural aged tobacco; 2) when the dosage of the enzymes was constant, the nicotine content in treated tobacco was decreased with the increase of treatment time, but almost no change was found after four days; 3) there was a negative correlation between the dosage and nicotine content, namely, the more enzymes was applied, the less nicotine remained in treated tobacco; 4) in terms of degradation of nicotine in tobacco, enzyme was more effective than microorganism, besides, enzyme treatment was more controllable.