In this paper, a highpressure rotary joint which can be used in highpressure condition is designed. The fluid domain is extracted from ANSYS and its structure is simulated by the Fluent. The total inlet flow rate of rotary joint is 150 L/min, and the outlet pressure is 240 MPa. The velocity and pressure distribution of the internal flow field of the pipeline are obtained by simulation, and the fluid calculation results are introduced into the solid structure for static analysis, and the deformation and equivalent stress of the solid structure are obtained. According to the simulation results, the structure of the rotary joint is optimized and simulated again. Through the comparison of the two simulation results, it shows that the pressure in the fluid domain gradually decreases with the flow direction of the fluid medium, and the velocity peak appears at the junction of the flow channel. The local stress and deformation of the joint are reduced after optimization，which has a certain reference value for the design and optimization of highpressure rotary joint.