The dimple plate heat exchanger (DPHE) has garnered attention in air-conditioning and heat pump industry due to its excellent performance. However, it is insufficient for the current research on its thermal-hydraulic performance and internal flow mechanism by varying structural parameters. In this study, numerical simulations are conducted based on flow and heat transfer cells with different dimple depths and pitches. The enhanced wall function k-e turbulence model is employed to analyze the variation of heat transfer and frictional performance with different dimple parameters. And the internal flow mechanisms and entropy generation within the different cells are presented. The results show that the overall heat transfer factor (F) of the dimple structure approximately increases by 97.5% with the depth range of 0.7-1.5mm, while F decreases by 11.3% with the pitch of 2.8-6.0 mm. The heat transfer coefficient is more sensitive to the change in dimple depth compared to pitch. The turbulence zones within the XZ cross-section of the cell emerge and gradually shift toward the wall as the dimple depth increases or the dimple pitch decreases, which is accompanied by higher entropy generation within the cells. The new findings in present study can contribute to DPHE design optimization and promote DPHE to more practical application.