Molten salt heat storage tank system capable of improving volume utilization rate

The utility model discloses a fused salt heat storage tank system capable of improving the volume utilization rate, and solves the problems of how to save the occupied space and effectively utilize the volume of a tank body under the condition of meeting field use. A traditional cold storage tank and a traditional hot storage tank are combined into a whole, only one fused salt heat storage tank is arranged, high-temperature fused salt is stored in the lower portion of the heat storage tank, low-temperature fused salt is stored in the upper portion of the heat storage tank, and a floating heat insulation plate is arranged between the high-temperature fused salt and the low-temperature fused salt in the tank; during heat storage, low-temperature fused salt is output from the top of the tank, and flows back to the fused salt heat storage tank from the bottom of the tank after being heated by the heat storage heat exchanger for energy storage; during heat release, the high-temperature fused salt is output from th