The embodiment of the invention discloses a shore power cable overload protection system for a marine shore power box, and the system comprises a circuit breaker; a power main line which is connectedwith the input end of the circuit breaker; s shunt release which is used for controlling the on-off of the circuit breaker; a plurality of shore power cables which are connected with the power supplymain line through wiring terminal strips; a multi-gear selection switch which is used for controlling the access number of shore power cables; a plurality of current transformers and a plurality of relays, wherein each relay is connected in series with one current transformer to form a control loop; a current transmitter which is connected with one of the current transformers; according to the invention, the demand of the ship for shore power for a long time is reduced; the number of actually connected shore power cables can be smaller than the number of cables in full load, a circuit breakerarranged on an original circuit does not need to be replaced, the workload of ship cable connecting personnel is reduced, overload protection can be provided for the connected shore power cables, cable overload or heating or fire accidents are prevented, and the safety of supplying power to a ship by shore power is ensured.