Abstract: In order to allow the energy stored in the battery of electric vehicles to focus more on driving the wheels instead of heating the cabin in winter,a compact on-board heat storage device based on Al-Si alloy phase change material was designed and built,which can be used to control the temperature of battery and cabin in cold weather. In this study,Al-12%Si（mass fraction of Al is 88%,mass fraction of Si is 12%）was used as the phase change heat storage material,and the heat charging,discharging and preservation performance of the heat storage device were experimentally studied. The results show that the maximum heat dissipation power is 324 W,the mass energy density and volume energy density of the heat storage can reach 189 Wh/kg and 165 Wh/L,respectively,,and the heat storage rate is 90.6%. In the heat extraction experiments,when the inlet air flow rates are 60,80 and 100 m3/h,the heat utilization rates are 84.9%,88.2% and 93.2%,respectively. When the air flow rate is 60 m3/h and the air outlet temperatures are 70 ℃ and 50 ℃,the heat utilization rates are 76.0% and 54%,respectively. The heat storage device has good thermal insulation performance,high energy density and high thermal efficiency,which can provide a reference for the miniaturization design of electric heating high temperature phase change heat storage devices.