Thermoelectric generators (TEGs) are widely used in many industries. The voltage and output power of TEG chips are critical indicators to evaluate the performance of TEGs. The conventional method is to directly test the output voltage and power of the whole TEG chip that contains 127 pairs of P- and N-type (PN) legs (127-PN-TEG). However, the assembling of these PN legs is very time-consuming. In order to reduce experimental time and the consumption of TEG materials, we proposed an experimental method. We developed the test apparatus for the rapid evaluation of TEG performance using a TEG chip with a single pair of PN legs (1-PN-TEG). We made several 1-PN-TEGs and 127-PN-TEGs using the same thermoelectric material (bismuth telluride). We then measured the voltage and the power of these 1-PN-TEGs and 127-PN-TEGs, respectively. The experimental results were compared and analyzed. The comparison showed that the voltage of 127-PN-TEG is equal to the voltage of 1-PN-TEG times 127, which implies that we could use the test data of 1-PN-TEG to evaluate the performance of 127-PN-TEG. Using the experimental device developed in this paper, we also studied the effects of the PN leg area (cross-sectional area of PN legs) and the pressure applied over the TEGs on the output power of 1-PN-TEG. The experimental results showed that the power per unit area decreases with an increase in the 1-PN-TEG's PN leg area when the temperature difference between the hot and cold sides was constant. Under specific temperature difference conditions, the open-circuit voltage and the output power will increase with the pressure applied on the TEG chips.