The utility model discloses an air inlet energy-saving device of isothermal heat treatment equipment, which comprises a cooling mechanism and a heat preservation energy-saving mechanism, the cooling mechanism is arranged above the inner wall of a channel, and the heat preservation energy-saving mechanism is arranged at an air inlet of the isothermal heat treatment equipment; the heat preservationand energy saving mechanism comprises a frame and a plurality of parallel blade assemblies arranged on the frame, the shape and size of the frame are matched with those of the cross section of the airinlet, each blade assembly comprises a blade and a connecting rod connected with the blade, and the blades are fixedly connected with the frame through the connecting rods. And the blades are drivenby the cooling mechanism to turn over at multiple angles by taking the connecting rod as a rotating shaft. According to the utility model, the blades in the heat-preservation energy-saving mechanism can be driven by the driving mechanism to be randomly adjusted at multiple angles, so that a quenching medium tank is cooled; when the driving mechanism is closed, a heat preservation effect is achieved on the quenching medium tank, meanwhile, the temperature rising frequency of the quenching medium tank is reduced, and fuel gas losses are reduced.