Abstract: The oil loading system, the type of pressurized vessel is a device which on-off control of oil pump is manipulated by using the feature of compression of gas inside the vessel and even pressure transmission of liquid. It is adapted for the oil base operation of frequently interval manipulation, non-oven supply intensity, no flow by gravity, great supply. The advantages are stable in loading pressure, small in pressure surge, simple on autocoatrol, economic, easy to mainlenance. The article introbuces the technology system, operation principles of pressurized vessel, determination of vessel volume, level control, inflation method, configuration and principles of control devices (the buffer devices included), which give reference to design and operation.