The invention discloses a high-efficiency chemical composite circulation gas turbine device and a control method. The high-efficiency chemical composite circulation gas turbine device comprises a gascompressor, a fuel cell, a combustion chamber, a heat exchanger, a hydrogen source, a supercharging turbine, a power turbine and a power generator. The input end of the gas compressor communicates with the atmosphere, the first output end is connected with the first input end of the combustion chamber, and the second output end is connected with the second input end of the combustion chamber through the heat exchanger. The cathode input end of the fuel cell communicates with the atmosphere, the anode input end of the fuel cell is connected with the hydrogen source, the cathode output end is connected with the atmosphere through the heat exchanger, and the anode output end is connected with the third input end of the combustion chamber. The fourth input end of the combustion chamber is connected with the hydrogen source through a pipeline, the output end is connected with the input end of the supercharging turbine, the output end of the supercharging turbine is connected with the inputend of the power turbine, and the output end of the power turbine is connected with the power generator. According to the gas turbine device and the control method, the structure is simple, efficiencyis high, design is reasonable, sufficient tail gas utilization is achieved, and waste is avoided.