Abstract: A kinetic model was developed for two-liquid-phase culture of Taxus chinensis var. mairei for two-stage taxol production in flasks, and the model parameters were regressed with the experimental data. The simulated curves were in good agreement with the experimental data. Therefore the parameter organic solvent toxicity (10/lg P ) put forward by this paper made the mathematical model not only represent correctly the effects of toxicity of organic solvent and phase equilibrium constant for different organic solvents (paraffin, organic acid, alcohol and ester) and their volumetric fractions on cell growth and taxol production in the two-stage and two-liquid-phase culture, but also represent correctly the kinetics of the two-stage and one-liquid-phase culture (10/lg P =1). The mechanism of these effects was analyzed thoroughly by using the model.