The efficient and environmentally friendly air conditioning system plays a vital role in cost reduction and efficiency improvement within the shipping industry. This study focuses on a specific ocean-going container ship equipped with the 8S90ME-C10.2 marine diesel engine as its main propulsion system. Firstly, the cooling load of 149.56 kW and a wet load of 18.04 g/s for the container ship were calculated to determine an energy-efficient and comfortable air conditioning scheme. Secondly, a novel combined system, integrating temperature and humidity solution dehumidification with enhanced transcritical CO2 refrigeration using injection subcooling, was proposed. The regenerator for solution dehumidification and the generator for injection refrigeration utilized the main cylinder liner cooling water as a heat source. Based on the system modeling, numerical simulation, and result validation, comprehensive analyses and quantitative evaluations were conducted to investigate the sensitivity of temperature and humidity regulation parameters, system performance, components exergy efficiency, and economics. Finally, employing a multi-objective optimization algorithm, the optimal operating conditions and corresponding objective functions for the system were obtained: exhaust pressure of 9.43 MPa, regeneration temperature of 91.08 degrees C, subcooling degree of 19.48 degrees C, coefficient of refrigeration performance of 3.697, exergy loss of 84.136 kW, and an annual operating cost of $111,300. This combined system exhibits high efficiency, environmental friendliness, and comfort, making it well-suited to handle the fluctuating heat and humidity loads during the ocean-going container ship through varying sea climates.