Abstract: When membrane-separator cascade is employed to produce some species of high purity gases, the withdrawal removed from impurity end would be too small， which inflicts unfavorable effects on cascade’s operation and control, and therefore a new type of operation method, that is cascade to be operated with intermittent impurity-withdrawal, was adopted. Based on the calculation model of membrane-separator cascade, the dynamic simulation of parameter for membrane-separator cascade with intermittent impurity withdrawal was completed by using dynamic numerical methods. Simulation results show that the purity of gas purified can be up to 99.999%, nevertheless trace of target component is removed along with the impurity withdrawal. Overall, membrane-separator cascade with intermittent impurity-withdrawal can achieve a larger amount of impurity flow, while maintains a good purification performance and relatively small loss of target component, which indicates that the operation method is reasonable and viable.