Abstract: In order to improve the comprehensive performance of plate heat exchangers, numerical analysis was conducted on the flow and heat transfer of a certain gas-to-gas plate heat exchanger. The dimensions of the heat exchange plates in this heat exchanger are 1 530 mm in length and 750 mm in width, with a spacing of 12 mm between the plates, and the cold and hot fluids were exchanged in the form of cross flow. The dimpled heat exchange plate has two height dimpled of 6.0 and 3.5 mm, which are arranged and combined according to a certain law, to optimize heat exchange efficiency, where in the 6.0 mm concave pits and convex cells are the supporting contacts of the cold and hot fluid channels respectively. Using high temperature flue gas and air as heat exchange media, and conducting detailed simulation calculations and analysis, the heat transfer performance of 6.0 mm concave pits and convex cells is better than that of 3.5 mm concave pits and convex cells. Therefore, improvements were made to the heat exchange plates, and after replacing all 3.5 mm dimples with 6.0mm dimples, the number of dimples of 6.0 mm is increased from the original 42 to 189. The plate design scheme of longitudinal, herringbone and transversel arrangement of the support contact of the hot fluid channel is proposed. The Nussel number Nu, the flow resistance of the channel, the Performance Evaluation Criterion (PEC) of heat transfer performance and the pressure difference between the two sides of the plate are calculated under different flue gas flow rates. The research results indicate that: In the design condition, compared with the original plate structure, The longitudinal arrangement structure of the improved dimpled plate heat exchanger have shown significant improvement in performance. Specifically, the heat transfer performance evaluation criterion is 1.25, the pressure drop from 277.02 Pa to 308.31 Pa, the increase rate is 11%, the Nu is increased from 11.48 to 15.21, and the heat transfer performance is increased by 32%. Compared with the other two improved plate heat exchangers, the new plate with longitudinal arrangement structure has the smallest maximum pressure value, so the new plate is the best scheme for the improved design. Through in-depth simulation analysis of key factors such as heat transfer, flow and pressure, the above research proposed a new dimpled arrangement design scheme, which significantly improved the comprehensive performance of the plate heat exchanger. The research has important practical significance and application value in guiding the design of dimpled plate heat exchanger engineering, improving the efficiency of secondary energy utilization, responding to increasingly severe energy crises and environmental challenges, and promoting sustainable development.