The purpose of the invention is to provide a single-engine double-propeller gas-electric hybrid ship power system with a fuel cell. The system includes a gas engine, a generator, motors, the fuel cell, a storage battery, clutches, a gear case, propellers, a natural gas storage and supply device, a substation device, a shore power device, a ship power grid, and a ship load. The gas engine is connected to the gear case through the clutch. The motors and the generator are connected to the gear case through the clutches. The propellers are directly connected to output ends of the motors. An electric power source is the fuel cell, the storage battery and the generator. The single-engine double-propeller gas-electric hybrid ship power system with the fuel cell adopts a plurality of energy form arrangements, has a plurality of working modes, can meet requirements of ships in various environment and working conditions, can maintain the gas engine and the motors in a high efficiency zone all the time, reduces the fuel consumption and discharge of the ship power system, improves the power response of ships, and enlarges seaworthiness of the ships.