Abstract: A mathematic method for estimating disposition kinetics of sophocarpine in rats was proposed with combination of linear system analysis and physiological pharmacokinetic model. The results showed that the mathematically simulated values were in agreement with the observed values in rats. The simulated concentration values in rabbit plasma, following iv 25 mg and during infusion of 2.5 mg/min, from a scale-up of 250 g rat to 2.5 kg rabbit, were in accordance with the observed values.The mean transfer time in tissues, the mean circulation time and the mean disposition time of sophocarpine in rats were estimated. The mean circulation time and the mean disposition time in rats were 7.34 and 50.7 min, respectively. The predicted mean disposition time of sophocarpine in rabbit was 69.4 min, which was in reasonable agreement with the observed value 85.8 min.