Objective：To establish the mathematical model and computer simulation for the physical process of end-inspiratory plateau ventilation. Methods：The physical process of end-inspiratory plateau ventilation, which is divided into inspiratory phase, end-inspiratory pause phase, expiratory phase and end-expiratory phase, was analyzed to deduce mathematical functions, by using hydromechanics theory. Then simulation curves were carried out by computer based on the mathematical model. The simulated curves were compared with those which were from clinical monitoring. Results：The mathematical functions of the flow velocity (v), flow rate (Q), pulmonary volume (Vt), alveolar pressure (PA) and airway pressure (Paw) changing along with the time (t) during the mechanical ventilation process, have been gotten. The theory curves obtained by computer simulation were much the same as the workings curves from clinical monitoring. Conclusion：The mathematical model for the physical process of end-inspiratory plateau ventilation can be established undoubtedly. The computer simulation of model can reproduce the clinical working curves of some kinds of ventilators.