The invention discloses a photoelectric conversion storage device, which comprises a heat insulation layer, a phase change energy storage material layer, a thermoelectric material layer and a heat dissipation layer, wherein the lower part of the heat insulation layer is sealed with the upper surface of the thermoelectric material layer to form a covering space, the internal part of the covering space is vacuumized, the phase change energy storage material layer is accommodated in the covering space, the phase change energy storage material layer forms good heat conduction connection with the upper surface of the thermoelectric material layer, the heat dissipation layer forms good heat conduction connection with the lower surface of the thermoelectric material layer, the upper surface of the thermoelectric material layer is a high temperature surface, and the lower surface of the thermoelectric material layer is a low temperature surface. The invention further provides a preparation method of the photoelectric conversion storage device. Compared with the traditional photovoltaic technologies, the photoelectric conversion storage device can realize continuous work in the case of interrupted solar energy and can store energy by itself, thereby effectively improving the utilization efficiency of solar energy, reducing the storage cost, and having broad application prospects in thetechnical field of green energy.