The invention discloses a heating device of a laminating machine. The heating device comprises a housing, wherein three layers of heating tubes are parallelly arranged in the housing, the top-layer heating tubes and the bottom-layer heating tubes are symmetrically arranged, the middle-layer heating tubes and the heating tubes on two sides of the middle-layer heating tubes are arranged in a staggered mode, a temperature sensor is arranged between the two adjacent middle-layer heating tubes, the housing is filled with a heat-conducting silica gel layer, the heat-conducting silica gel layer is provided with arc-shaped grooves at the positions of the top-layer heating tubes and the bottom-layer heating tubes, and the top-layer heating tubes and the bottom-layer heating tubes are located in the arc-shaped grooves. Each heating tube comprises an outer sleeve and an inner sleeve which are arranged concentrically, heat-conducting oil is filled between the outer sleeves and the inner sleeves, and electric heating wires are arranged inside the inner sleeves. The invention further discloses a control method of the heating device of the laminating machine. The shortcomings of the prior art can be overcome, and the temperature difference of the heating device of the laminating machine is further reduced.