Abstract: Choked flow is an extreme condition of the valve, which presents a complex multiphase flow state and is often used to calibrate important characteristic parameters of the regulating valve. In addition, the choked flow will cause great damage to the valve and seriously affect its service life. Therefore, it is very important to study the choked flow of the valve. In order to study the choked flow characteristics of the plunger valve, a two-phase flow analysis simulation model of the plunger valve was established based on the method of computational fluid dynamics, and the accuracy of the model was verified by comparison with the experimental data. According to the simulation model, the choked flow rate of the plunger valve and liquid pressure recovery coefficient were obtained. Finally, according to the simulation results, the choked flow is studied. The results show that the liquid pressure recovery coefficient of the piston valve is 0.86, the initial cavitation coefficient is 2.45; the cavitation index of the piston valve is 1.11 when the flow is blocked. The pressure on the wall surface of the throttling element and in the center area of the jet is too low, and serious flashing and continuous two-phase flow are the reasons for the blocked flow. This research establishes a method for visualization of choked flow and valve characteristic parameter acquisition based on simulation technology, which has great significance for the research and application of control valves.