A novel thermoelectric generating and performance measuring system (TGPMS) was designed and fabricated. TGPMS can not only achieve the function of thermoelectric generation, but also measure the thermoelectric performance parameters of the bismuth-telluride-based thermoelectric device accurately. These thermoelectric performance parameters mainly include the dependence of the Seebeck coefficient of the thermoelectric device on the device's temperature in the low temperature range (about 40～190℃), and the dependence of the power output and thermoelectric conversion efficiency on the temperature difference or output load. With the optimum load, the optimal value of the power output is 3.39W when the temperature difference reaches 231.2℃, and the optimal value of the conversion efficiency is 3.22% when the temperature difference reaches 208.9℃. TGPMS provides an experimental foundation for the application of the thermoelectric generators in the space field.