The sealing test base of the reciprocating high pressure oil liquid placed vertically was designed based on the valve body itself of the digital liquid force decoder, and the sealing performance and friction characteristics of the decoder under different medium pressure, reciprocating speed and compressibility were investigated through the test method. As a result, in the case of high pressure, the digital hydraulic force decoder requires a large activation force, and when the starting force does not reach the maximum static frictional force, there is a certain delay phenomenon in the operation response, and at the same time, the large delay frictional force can aggravate the follow-up of the sealing system; the maximum static friction force and the sliding friction force increase linearly with increase in medium pressure, and the growth rates between 0 to 16 MPa and 16 MPa to 32 MPa are different, and the growth rate becomes smaller at 16 MPa to 32 MPa; leakage at high speed is likely to occur in the seal portion of the decoder; the initial compression rate has a clear effect on the sealing performance of the decoder, and if the initial compression rate is 23.25%, it is possible to satisfy the sealing request at the normal operation of the decoder.