Abstract: To investigate the heat transfer characteristics of the supercritical CO₂ cycle pre-cooler, the design and heat transfer characteristics of the 600MW coal-based supercritical CO₂ cycle PCHE pre- cooler are studied in a variable structure segmental design model. The design parameters of the pre-cooler are optimized and determined under constant heat flow, and the internal heat transfer characteristics are discussed. The results show that S-CO₂ pseudo-critical conditions in the pre-cooler make the temperature variation non-linear; the influence of the hot-side properties on the overall heat transfer performance in pre-cooler is more significant; a 3 times increase in the inlet mass flow of the hot side can increase the average heat transfer coefficient by 54.21% but it will decrease the minimum temperature difference by 53.38%, and the increase in cold-side inlet mass flow rate only enhances cold-side heat transfer. It is recommended to choose the volume as the optimization target to determine the number of cross-sectional channels and hot-side inlet parameters, and the determination of the cold mass flow should be a balance of both size and pressure drop; the inlet mass flow of single channel in the cold and hot side of the pre-cooler is selected as 2.2g/s and 0.75g/s, respectively, which reduces the volume of the pre-cooler by 10.50% and increases the minimum temperature difference by 1℃.