The invention creatively discloses a solar thermal storage device with reasonable design and simple structure. The thermal storage device stores solar heat for heating or hot water supply. At the sametime, the device has an auxiliary electric heating function to ensure that heat is supplied in time when solar energy is insufficient to make up for the shortcomings of traditional pure solar thermalstorage devices. The solar thermal storage device comprises thermal storage rods, vacuum transparent glass sleeves, solar heat-absorbing coatings, a heat exchange cavity, and thermal storage materials. The solar thermal storage device is characterized in that each thermal storage rod is rod-shaped on the whole and is hollow, one end is a thermal dissipation section, the other end is a thermal storage section, and the outer surface of the thermal dissipation section is provided with a plurality of thermal dissipation fins; the vacuum transparent glass sleeves are sleeved on the thermal storagesections, and the thermal storage materials are sealed in the thermal storage sections; the solar heat-absorbing coatings are arranged on the outer surfaces of the thermal storage sections or the inner surface layers of the vacuum transparent glass sleeves; and the plurality of thermal radiation sections are uniformly arranged in the heat exchange cavity, which has the heat preservation function,and is provided with a fluid inlet and a fluid outlet.