The invention relates to a heat energy circulating system of a coating production line, which comprises a heating water tank of a pre-treatment system of the coating production line and a drying box of a drying facility of the coating production line, wherein a stainless steel inner container and a combustor are fixed in a furnace body; the combustor is fixed to the lower part of the stainless steel inner container; an air outlet of a circulating calorifier is communicated with the furnace body; an atmosphere communicating vent opening into atmosphere directly is arranged at the top of the furnace body; a water outlet pipe and a return pipe are arranged on the stainless steel inner container; a hot-water circulating pump is arranged on the water outlet pipe; the water outlet pipe is communicated with hot-water inlets of the heating water tank of the pre-treatment system of the coating production line and the drying box of the drying facility of the coating production line; and hot-water outlets of the heating water tank of the pre-treatment system of the coating production line and the drying box of the drying facility of the coating production line are communicated with the return pipe. The heat energy circulating system has the advantages of completely eradicating the phenomenon of the negative pressure of a loop and a water outlet pipe and solving the problems of the cavitation of the water circulating pump and the water attack of the system along with good anti-explosion performance and convenient overhauling.