This device conducts external hydrostatic tests on various high-pressure gas cylinders. It uses an industrial control computer to control the entire set of operation tests including empty cylinder weighing, water filling, full cylinder weighing, and hydrostatic tests. Through these tests, the volumetric residual deformation rate of the gas cylinders can be accurately measured to ensure their safe use. The product is designed and manufactured in accordance with GB/T9251-2021 "Test Method for Hydraulic Pressure of Gas Cylinders". It is applicable to the regular inspection of compressed natural gas cylinders and cylinders of different types and specifications.