Closed pressure maintaining coring is a special coring technique that can maintain or approach formation pressure， allowing fluid and gas in the core to remain in their original state.This technology is of great significance for correctly understanding geological conditions， calculating recoverable reserves of oil fields， analyzing the mechanism of shale gas and coalbed gas reservoirs， and formulating exploration and development plans.TKP194-80 type sealed pressure maintaining coring tool is developed， which adopts key technologies such as large bore high pressure ball valve sealing， sealing fluid plugging， hydraulic differential migration， piston pressure compensation， and is equipped with core post-processing processes such as core freezing， cutting， and gas gathering. The outer diameter of the drill bit is 215mm， the pressure maintaining capacity is 50MPa， and the core diameter is 80mm.The application of pressure retaining coring was carried out in a coalbed methane resource geological exploration well in Jinzhong， Shanxi province. A total of 8 pressure retaining coring barrels were carried out， with a total footage of 37.51m. The core recovery rate was 84.4%， and the pressure retaining success rate was 87.5%.The research results show that the coring tool has reliable pressure retaining performance， feasible technical scheme， and meets the design requirements. It can provide technical equipment support for the exploration and development of conventional and unconventional oil and gas reservoirs.