Abstract: In order to make full use of waste tobacco, the technological parameters, including extracting pressure, temperature, time, flux of CO₂, the composition and volume of the entrainer, for the extraction of nicotine in waste tobacco with supercritical CO₂ fluid and their effects on the yield and purity of extracted nicotine were investigated.The optimal extracting conditions were as follows:the pressure was 23-25MPa, temperature 50-55℃, time 150-180miniutes, flux of CO₂ 16-18 litres per hour, entrainer 70%-80%(v/v) alcohol and the mass ratio of tobacco to entrainer was 1:4-6.The results showed that under such extracting conditions, the yield and purity of nicotine were > 90% and up to 70%, respectively.