Abstract: Seal is the key to determine the service life of cone bit. However, the passive seal is seriously worn, thus limiting the improvement of speed and service life of the cone bit. The basic principle of combined spiral seal structure with active sand discharge function is analyzed, and combined with the basic theory of fluid-solid coupling, the corresponding control equations are established. The performance of combined spiral seal is studied by the combination of finite element simulation and experiment. During finite element simulation, the simulation model is established, and the fluid-solid coupling simulation of the combined spiral seal is performed using the ANSYS simulation software. The sand discharge function of the single spiral seal is analyzed using the flow field pressure of spiral seal, and the sealing ability of the combined spiral seal is analyzed using the contact pressure of its O-ring. Moreover, the sand discharge performance verification test is designed for non-pressurized single spiral seal ring, so as to verify the sand discharge capacity of single spiral seal; the sealing performance verification test is designed for pressurized combined spiral seal; the practical application of spiral combined seal is studied by simulating the real drilling conditions on an indoor bench. The simulation and test results show that single spiral seal ring is applicable for sand discharge, and the combined spiral seal has good sealing ability.