Thermoelectric generator (TEG) system as a burgeoning method for light-duty automotive waste heat recovery has drawn the researcher’s attention for the last decade with the advantages of no moving parts and high reliability [1]. However, the low heat to electricity conversion efficiency is the key drawback that prevents the TEG from wildly using in practice. Furthermore, the efficiency of heat to electricity conversion for thermoelectric (TE) material is in the sharp of parabola, which means TE materials have a peak point of conversion efficiency and a best range for working temperatures. As a result, during most of the time in vehicle driving, the TEMs will not perform at their best range for working temperature and affect the efficiency of TEG system subsequently. Although there are plenty of researches focusing on the improvement of efficiency for the (TE) material, there are rare researches regarding the heat transfer enhancement on the system level, especially for the transient performance improvement for TEG.