Abstract: In order to analyze the difference in flow and heat transfer performance of plate-fin heat exchangers under low temperature conditions and normal temperature conditions, as well as the influence of fin interrupted length, a numerical model of heat transfer and flow of helium gas in serrated fin-channels was established, and numerical simulation analysis was carried out. The results show that the heat transfer performance of low-temperature helium gas in the serrated fins channels is superior to that of normal-temperature helium gas. When the helium gas inlet temperature is 20 K, the j factor increases by 1.1% to 55.9% compared to 300 K, and increases by 0.41% to 13.01% compared to 77 K. When the helium gas inlet temperature is 77 K, the j factor increases by 0.53% to 38.47% compared to 300 K. The flow performance of low-temperature helium gas in the serrated fins channels is worse than that of normal-temperature helium gas. When the helium gas inlet temperature is 20 K, the f factor is 16.84% to 28.87% higher than that at 300 K, and 3.98% to 23.19% higher than that at 77 K. The fin interrupted length has a significant impact on the heat transfer and flow performance of the fins in different temperature regions. In different temperature regions, the j factor decreases with the increase of fin interrupted length, while the f factor increases with the decrease of fin interrupted length. When the Reynolds number is low, the JF factor increases with the decrease of fin interrupted length, while the opposite trend appears when the Reynolds number is high.