The plunger type fluid pump has the advantage of high work pressure, it is widely used in the field of fluid transportation, pressure cleaning and power transmission.However,for the piston pump that used in fluid transfer, the impurities in fluid medium will aggravate the plunger pair wear and seal failure, and greatly reduces the working life of the pump. A plunger sealing form based on gas isolation was proposed.The liquid medium and sealing ring were separated by a pressurized gas film, in order to prevent the impurities(corrosive liquids) from entering the friction.By using the gas isolation,not only the life of piston pair was improved,but also leakage of liquid medium was avoided.FLUENT software was used to calculate the seal flow field parameters of new sealing technology.The flow field performance of the two processes that the liquid was discharged and absorbed by increasing the pressure and reducing the pressure was analyzed. The sealing principle was validated to be feasible.