This paper proposed an adaptive protection scheme for ship grids. The scheme was designed by offline and online computing. Offline calculations produced the protection setting values in all operation conditions， and the settings were  stored in a central control system. Online calculations assembled the operation data in a real-time way and identified the network topology. From the available settings, the corresponding values were chosen from the matching of operation conditions. A typical modelling for over-current adaptive protection were established, whose results proved the correctness and effectiveness of the scheme.