The invention discloses an activated carbon filter coupling solar energy driven device for treating bitter salty water through membrane capacitive deionization and an application method thereof, and belongs to the technical field of bitter salty water treatment. The problems that MCDI electrode organic pollution is serious, effluent quality is poor and non-renewable energy resources are used for supplying power of an existing method for treating bitter salty water through MCDI are solved. The device comprises a raw water tank, a check valve, a raw water inlet valve, an activated carbon filter, a drainage valve, a back washing water storage tank, a back washing valve, intermediate water tank, an MCDI water inlet valve, an MCDI assembly, a regeneration valve, a concentrated brine storage tank, a fluid flowmeter or water meter, a water outlet valve, a clean water tank and a solar power supply system. According to the device, gravity flow exists in the whole application process, the water supply power cost is saved, meanwhile, working pressure is low, clean and renewable solar energy is used as the power supply, and power saving and environmental protection are achieved; effluent quality is improved, and MCDI organic pollution is avoided; operation is easy, the maintenance rate is low, and no chemical agent exists.