The utility model discloses an automobile exhaust semiconductor power device of coupling phase transition energy storage, including the heat transfer box that supplies tail gas to pass through, be provided with the radiating fin block structure on the heat transfer box inner wall, shown radiating fin block structure varies radiating fin by a plurality of height and constitutes, the concrete arrangement form that a plurality of height vary radiating fin does: radiating fin is the highest at the middle part, and be arithmetic progression toward the both sides height and steadily decrease, and itis highly the same along the radiating fin of middle part symmetric position, heat transfer box surface is provided with the independent sealed container of branch, divide independent sealed container the inside foamed metal composite phase change material for energy storage that is equipped with, divide the independent sealed container outside to be connected with difference in temperature thermoelectric generation module's hot junction, difference in temperature thermoelectric generation module's cold junction and heat dissipation cooling passage are connected, heat dissipation cooling passage is connected with the cooling water box through the shut pipeline. This device can provide stable heat source and heat source utilization rate height.