The multi-dimensional vibration test system is widely used in aerospace and aviation fields.It can provide three directions excitation force for aerospace and aerospace products,and simulate the vibration environment of the test piece more realistically.The performance of the decoupling device in the system has a significant impact on the overall system performance.The structure of the plane hydrostatic decoupling was designed and investigated based on the hydrostatic pressure technical index requirements.A set of plane hydrostatic pressure decoupling device was designed through theoretical calculation method,and the oil film performance test and dynamic performance test of the device were carried out.The test results meet the technical index requirements.It provides a theoretical basis for the structural design of the hydrostatic pressure decoupling device of the multi-dimensional vibration test system.