In order to explore the influence of structural parameters on the gap sealing performance of hydraulic rotary joints,the leakage and pressure loss were used as performance indicators of hydraulic rotary joints,and the effects of three main structural parameters,namely the effective length of seal,the diameter of seal,and sealing gap value, on the performance of rotary joints were studied.The method of combining orthogonal test and Fluent fluid simulation was used to analyze the leakage and pressure loss of the gap seal of hydraulic rotary joint under different structural parameters.The degree of influence of three structural parameters on leakage is in descending order:sealing gap value,the effective length of seal,the diameter of seal.The degree of influence on pressure loss is in descending order:the effective length of seal,the diameter of seal,and sealing gap value.The sealing gap value has a significant impact on the leakage rate,and the leakage rate increases exponentially with the increase of the sealing gap,while the effective length of seal and the diameter of seal have no significant impact on the leakage rate.The effective length of seal has an extremely significant impact on pressure loss, while the diameter of seal and sealing gap value have no significant impact on pressure loss.Overall,the sealing gap value,the diameter of seal,and the effective length of seal are in a linear function relationship with pressure loss,and the first two are positively correlated with pressure loss,while the latter is negatively correlated with pressure loss.