Abstract: On basis of Peltier and Seebeck effects,a type of electric transformer was designed,fabricated and tested for the application of voltage transformation at low frequency. The critical components of this transformer are two plate-like thermoelectric modules. Among them,one thermoelectric module acts as input side to convert electric energy into thermal energy,another module works as output side to convert thermal energy into electric energy. Therefore,the electric transformation principle of the thermoelectric transformer is remarkedly different from that of traditional electromagnetic and piezoelectric transformers.The investigation indicates that when the frequency of input voltage is 0. 01 Hz,the transformation ratio is 47. 70 and 0. 31 for the bucking and boosting modes,respectively.