The design and principle of a self－adaptive fuse system are presented in this paper. Because the system can adapt to some uncertain fight conditions and parameters, it can precisely recognize target and realize the biggest destructivity of fight part with the best way, at the best time and the best distance. Some key problems in the system designing are analysed, including small field of view probing way of three branches, accurately taking of light signal criterion time, anti－jamming of ocean wave and recognizing the situation of ocean surface. The scheme diagram and software flow chart are also presented. All parameters of the system reach the designing requirement and are verified in the test.