In this paper, the thermoelectric performance and mechanical reliability of a segmented annular thermoelectric generator under steady state and transient conditions are investigated. The influence of structural parameter on the performance of segmented annular thermoelectric generators is discussed, the optimized design with high thermoelectric performance and reliability is obtained. These results present that with the increase of the structural parameter, the output power of segmented annular thermoelectric generators increases first and then decreases, and the max von Mises stresses in the hot-segment and cold-segment will always achieve an optimal value when the temperature in the hot end is larger than 300 degrees C. In addition, compared with the single-Skutterudite annular thermoelectric device, the. output power of segmented annular thermoelectric generators can improve 18.3%, the max von Mises stress in the hot-segment is decreased by 12.5%. Finally, the thermoelectric performance and reliability of segmented annular thermoelectric generators operating in a sinusoidal heat source are investigated. The results show that the smaller the period and amplitude of the heat source, the better the overall performance of the segmented annular thermoelectric generator. These obtained results may provide some useful guidance for the application of segmented annular thermoelectric generators in the waste heat recovery. (C) 2019 Elsevier Ltd. All rights reserved.