This research is to design a preservation and heat storage device for baby food. The functions of preservation and heating are usually separated in two products (one product one function) in current market, such as tiny refrigerator and food heating device. However, for the newborn mothers, they expect to carry lighter weights and to feed the baby more easily. As a result, the main purpose of this research is to invent a device which combines the functions of preservation and heating together, by using thermoelectric cooling chip to create freezing side and heating side. In addition, this research realizes the concept of using heat storage blocks with the phase change material inside to reuse the wasted energy come from heating side of the device. The design of heat storage blocks is verified by the experiments, besides; simulation of the phase change phenomenon in the heat storage blocks is also done with the ANSYS CFX to know the mechanism of phase change of phase change material in the heat storage block. After analyzing the position of heat source, the structure of heat storage blocks, and the efficiency of integrated device, a preservation and heat storage device according to simulation results will be designed and produced.