Thermoelectric module can be used as a generator to convert thermal energy into electricity, or as a cooler to convert electricity into heat. In this work, a comprehensive model is proposed to predict the performance of thermoelectric generator and cooler by setting different boundary conditions. Based on the proposed model, the influences of height, cross-sectional area, number of couples, ceramic plate, and heat loss on the generator and cooler are investigated. To balance the output performance and cooling performance of thermoelectric modules simultaneously, a comprehensive study on the thermoelectric module is conducted. The results indicate that (i) A relatively lower leg height enables the enhancement of output power, cooling power, and COP, despite a slight reduction in conversion efficiency; (ii) When increasing the total cross-sectional area of legs, thermoelectric generator should aim at adopting more thermoelectric couples, whereas the cooler should apply a larger area for every single leg; (iii) For the optimization of ceramic plates, more attention should be paid in improving the thermal conductivity. Also, fillers are not recommended for thermoelectric module in general environment. The findings of this work may guide the design and parametric optimization of thermoelectric module used for both power generation and cooling. (C) 2020 Elsevier Ltd. All rights reserved.