The pressure holding coring technology can keep the extracted core under in-situ condition， minimize the loss of important data in the core， and then accurately obtain important formation parameters which can calculate the reserves of mineral resources. In this paper， the ball valve mechanism of pressure core sampler is studied by numerical simulation， and its dynamic characteristics are explored to optimize the ball valve mechanism， and increase its sealing reliability. The results show that with the increasing of thrust force on the ball valve， the shorter the closing time of ball valve， but the vibration generated increases， which is easy to cause seal failure. Thus， the small thrust force is selected to help improve the sealing reliability. With the decreasing of friction coefficient， However， the vibration generated increases， making the leakage risk of ball valve much bigger. When the ball valve is closed， the pressure simulation of 30MPa is conducted. The maximum contact stress and the maximum strain are both within the allowable range of ball valve.This study are meaningful to guide the optimal design of ball valve mechanism and improve its working reliability.