Thermoelectric module (TEM) has been widely used to recover the waste heat contained in the fluid. However, its performance will be limited since all the thermoelements are connected in serial and the generated current each of them is not the same. To work out this deficiency, a novel TEM structure is disclosed, where the cross-sectional area of thermoelements is increasing gradually along with the hot fluid downward flow. Besides, this work develops a steady-state, three-dimensional and fluid-thermal-electric multi-physical model to evaluate the TEM performance. Based on the numerical results, the influences of different TEM structures, hot air temperature and mass flow rate on the TEM output performance are investigated. The results show that (i) Compared to conventional TEM, the novel TEM structure with the same quantity of thermoelectric material can reach a better performance when ATV = 0.01 mm or 0.02 mm, and the higher temperature and mass flow rate, the more gains of the novel TEM; (ii) Compared with temperature, mass flow rate has a much higher effect on the output performance of the novel TEM structure; (iii) The maximum output power occurs when the load resistance is slightly greater than internal resistance. Apart from that, the verification experiments are conducted and the results indicate a good agreement of the proposed numerical model. The findings of this work may provide a new idea to optimize the TEM structure and improve its performance.