Design three types of bottom flat rubber sealing gaskets, analyze the waterproof and compression performance of the sealing gasket through numerical calculations and physical model tests, and study the sliding deformation of the sealing gasket during the assembly process. Three types of cross-sectional studies show that: 1) there is an opening in the center of Section 1, which reduces the compression stress of the sealing gasket. After compression, the opening position cannot be fully closed, and the waterproof path of the sealing gasket is reduced, which is not conducive to the waterproofing of the pipe joint; 2) The waterproof capacity of section 3 is 30.1% higher than that of section 2, but the surface roughness of section 3 will be increased after being compounded with water swelling rubber. The assembly process is prone to exacerbating the accumulation and deformation of corner sealing pads, and multiple trial assembly may lead to water swelling and separation of EPDM from EPDM; 3) When the seal compresses and slides, the direction of movement is opposite. When the corner accumulation deformation is too large, it is easy to cause a large height difference between the sealing pads. When the next ring segment is assembled in a staggered manner, the sealing pad here is difficult to compress in place, which is prone to leakage in the seepage channel.