The purpose of the invention is to provide a dual-motor coaxial gas-electric hybrid ship power system. The system includes a gas engine, a generator, motors, a storage battery, a fuel cell, clutches,a gear case, a propeller, a natural gas storage and supply device, substation devices, 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 first motor and the second motor are connected to the gear case through the clutches. The generator is connected to an output end of the gear case. The two motors are connected to each other through a shaft. An electric power source is the storage battery, the generator and the fuel cell. The dual-motor coaxial gas-electric hybrid ship power system 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 gas engine, improves the power response of ships, and enlarges seaworthiness of the ships.