Abstract: When checking the pressure transmitter and differential pressure transmitter in compressor stations in West- to-East Natural Gas Pipeline in the past, the blow-off pipes on the pressure lead-in joint, two-valve group and five-valve group had to be disassembled, and then the transmitter was checked with calibration instruments. Through adding modified two-valve group to the pressure transmitter without two-valve group and adding a special joint to the blow-off pipe of the pressure transmitter and the differential pressure transmitter with two-valve group, the calibration of pressure and differential pressure transmitter without disassemble has been realized. In this way, the operation risks, such as the leakage of pressure lead-in joint after dismantling, screw thread sliding and stress created after the installation of pressure lead-in pipe, are avoided. Meanwhile, work load of the calibration worker and no standby time of the equipment in calibration period are reduced, the available rate of equipment is increased accordingly, which can provide a reference to the similar pipeline issues.