Aimed at the operating failure problem of a shaft end mechanical seal of the oil-gas multiphase pump on the offshore platform,the causes were analyzed,and the structure was improved.Through the performance test of the improved mechanical seal,the change of sealing performance with pressure the wear condition of sealing end face under different spring specific pressure conditions were compared and analyzed,and the change of sealing performance with pressure and rotational speed under different end face widths was compared and analyzed.The results show that reducing the spring specific pressure can slightly reduce the friction power of the seal end face,but it will increase the risk of leakage,and reducing the end face width can effectively improve the sealing performance under poor lubrication conditions.The optimal design parameters of the seal were determined,and the 100 h qualification test of the domestic sealing prototype was carried out.The stability of the friction power of the sealing end face and the leakage index during its operation were examined.The experimental results show that the friction power of the improved sealing end face is basically stable,with small fluctuations,and the leakage meets the standard index requirements.This verifies the rationality of the improved sealing structure,the effectiveness and the adaptability of operating conditions of optimizing design parameters.