High thermoelectric figure of merits have been achieved in lead telluride (PbTe) alloys recently, which are beneficial for future thermoelectric applications. In this study, a PbTe-based thermoelectric module is constructed by eight pairs of p-type PbTe-8%SrTe and n-type PbTe0.998I0.002-3%Sb legs with initial sizes of 3 x 3 x 3 mm(3). The relationship between multiple geometric parameters and performance of module has been studied by finite-element simulation. The maximum output power (P-max) of 7.6 W and efficiency (eta(max)) of 15.3% have been achieved at Delta T= 500 K for ideal contacted PbTe-based thermoelectric module. Contact resistance must exist in experimental thermoelectric module, so it has been considered in simulation about geometry optimization. The cross-sectional area ratio (A(p)/A(n)) and height (H) show strong dependent relationship to optimize module performance. The larger A(p)/A(n) and relatively lower H are propitious to enhance the output power. Moreover, the efficiency is improved at an optimum A(p)/A(n) and relatively higher H. In this PbTe-based module, the P-max = 4W is achieved at A(p)/A(n) = 1.78 and H = 0.65 mm, while eta(max) = 14% is achieved at A(p)/A(n) = 1.64 and H = 13 mm under Delta T = 500 K. The P-max and eta(max) are 20% and 65% larger than those of initial design sizes. Thus, geometric structure modification is a good way to improve the performance of thermoelectric applications. (C) 2019 Elsevier Ltd. All rights reserved.