Abstract: The spiral magnetic fluid composite seal structure of the cone bit is characterized by active sand removal and automatic compensation for slurry sealing effect, as being a new seal structure for cone bit. Pressure resistance is the key to determine the performance of this new seal structure. Therefore, the paper constructs a numerical simulation model of magnetic field and magnetic fluid coupling for the spiral magnetic fluid composite seal of cone bit, and the whole process of pressure resistance and sealing performance of the spiral magnetic fluid composite seal is achieved in terms of magnetic flux density, magnetic induction intensity and theoretical pressure resistance. The study focuses on the influence law of working condition parameters (speed and temperature)on the pressure resistance of the new seal. Numerical simulation reveals that the magnetic lines of force are densely distributed at the top of pole shoe, which can achieve poly magnetic effect, and the magnetic field intensity at the top of the pole shoe will be higher than that at the seal gap; the magnetic flux density at the top of pole shoe is significantly higher than that at the other positions; the magnetic induction intensity at the top of each pole shoe is high and similar, and the magnetic induction intensity at the top of pole shoe is the largest, and can reach up to 3.697 8 T, while that at both tooth space and seal gap is 0.24 T. In addition, there is a large magnetic induction intensity gradient at the top of pole shoe. The theoretically calculated pressure resistance value is 1.09 MPa, which has verified the feasibility of the seal structure design. As the speed and temperature rise, the pressure resistance of the whole seal structure drops. Compared with speed, temperature has less influence on the pressure resistance of the seal structure. The pressure resistance of the spiral magnetic fluid composite seal of cone bit is verified by experimental studies, and the influence law of working condition parameters on the pressure resistance is also revealed, from which it can be see that the experimental results are consistent with the simulation results.