In order to improve the fluid sealing performance of the radiation seepage shear box in the rock shear seepage experimental system,three sealing methods of the radiation seepage sealing device were proposed for the new rock shear seepage test device independently developed,including the sealing method of transverse pre-compression of sealing ring,the sealing method of normal compression of silicone pads,and the sealing method of normal pre-compression of sealing ring.The large deformation numerical simulation and experimental verification of the three sealing schemes were carried out.The results show that:(1)the effect of the transverse pre-compression sealing method of the sealing ring is independent of the normal load applied during the test,but is related to the flatness and parallelism of the upper end face of the rock sample.The fluid sealing pressure is relatively stable,and the sealing water pressure fluctuates around 0.72 MPa.(2) The sealing effect of the silicone pad of normal compression is positively related to the applied normal load.The pad objectively has a sealing pressure threshold within the allowable range of the normal load.The maximum value of the sealing water pressure can reach 1.62 MPa under the normal load of 3.3 MPa.(3) The sealing ring of normal pre-compression not only has the advantages of the silicone pad of normal compression,but also overcomes the defect of the silicone pad of normal compression that the sealing performance depends on the size of the normal load,and can achieve relatively good sealing effect under a lower normal load.The maximum sealing pressure can reach 2.45 MPa.The numerical simulation results indicate that for the normal pre-compression seal of the sealing ring,enlarging the diameter of the sealing ring cannot significantly improve the sealing performance,and changing the material of the sealing ring has a greater impact on the sealing performance.This research provides a theoretical reference for breaking through the limitation of 5 MPa water pressure seal of shear seepage test equipment and optimizing the structural design of shear box seal device.