The working conditions of marine gearbox are complex and changeable. The seals work under high speed, high temperature, high pressure, local negative pressure and vibration conditions for a long time. The wear and leakage of traditional mechanical seals and lip seals need to be solved urgently. In order to solve these problems, this paper studies the high reliability adaptive seal, establishes the adaptive seal structure model, and analyzes the mechanism of adaptive compensation wear gap and counteracting vibration impact load. Aiming at the causes of sealing failure of traditional gearboxes, solutions are proposed and an adaptive sealing test bench is built to verify and analyze the sealing performance. The experimental results show that the adaptive seal has good sealing performance, and the sealing performance of the sealing ring is closely related to the rotational speed, the pressure and the oil return rate. The research results reveal the sealing mechanism of adaptive seal and the influencing factors of sealing performance, which has certain guiding significance for the design of adaptive seal, and provides a new solution for overcoming the leakage problem of marine gearbox seal.