With the development of science and technology, large diameter, high temperature, high pressure resistant flat gate valve has been widely used. Due to the equipment and the size of the valve to be tested, many large-diameter flat gate valves can not be hydrostatically tested with a press, so the design of the pressure-measuring device is based on the characteristics of the valve. Large-diameter valve for hydrostatic test, the general method of blind bolts fixed bolt, the bolt preload to seal the formation of pressure to seal the seal than the pressure in order to achieve the valve inlet and outlet seal. The pressure F is applied. Under the action of the gasket, the initial compression is. . When the blind plate is subjected to internal pressure (in the opposite direction to F.), the gasket is relaxed and rebounds, reducing the amount of compression of the gasket, causing leakage when the gasket relaxes to a certain degree, as reflected in the sealing characteristic curve It is the minimum pressure required for sealing. In production, as long as the rational choice of gaskets, the rigid seal under the minimum pressure is easily satisfied. However, in actual production, due to insufficient rigidity of the blind plate, excessive deformation occurs under the effect of excessive end face pressure, the bolts are loosened and deformed, and the amount of compression of the gasket is excessively rebound, resulting in the sealing gasket being lower in pressure than the pressure to form a sealing leakage Cause pressure test failure. In order to achieve the safety and reliability of the hydrostatic test, it is generally realized by improving the rigidity of the blind plate and selecting the excellent gasket. But for large-diameter high-pressure valve pressure test, unlimited to improve the rigidity of the blind, the use of high-quality gaskets, in the implementation process will increase production costs, there are some limitations. In the case of pressure test to determine the pressure, only through a special structure to reduce the end face force area, to achieve the purpose of reducing the end face pressure. When the pressure on the end face is reduced, the minimum packing force of the gasket is correspondingly reduced, and the rigid requirement on the blind plate is also reduced correspondingly. Aiming at the problem of lack of rigidity of the pressure test device, its structure has been improved. Change the pressure-test blind to the pressure test cylinder, reduce the stress area of ​​the end surface through pressure test, and reduce the pressure on the end surface to reduce the preload of the washer so as to achieve reliable and safe hydraulic pressure test. The improved pressure test device after actual use, the effect is good, to solve the large-diameter high-pressure valve hydraulic test problems.