Abstract: The impulsive differential equation was used to study the changes of blood drug concentration for the two-atrioventricular model under multiple intravenous administration. The blood drug concentration changed periodically under the stable condition. Based on the drug safety window, the specific flow and algorithm steps of drug administration plan design were discussed.Further, combined with the blood drug concentration data of 24 tumor patients measured by experiment at different time series after a single intravenous injection of methotrexate, the pharmacokinetic specific parameters of 24 patients were estimated by the method of nonlinear regression analysis. The similarities and differences among patients were studied by using the patient-specific parameter values. Finally, based on the specific parameter values of different patients, the individualized drug administration plan was given.