The drug release model of the polymer microspheres was combined with the pharmaco-kinetics model.Drug release，absorption，and elimination were integrated in a general model，with which the drug concentration in plasma was estimated.Based on drug concentration profiles of a single dose，the superposition method was used to estimate the accumulation for steady state，by which the effects of drug release and dosing interval were evaluated.In comparison to oral administration of drug solution，the microspheres released drug at a sustained rate，generating much lower peak concentration，and the drug concentration fluctuation was also decreased significantly for multiple dosages.