The PCHE is an important heat transfer component for the coupling of the lead–bismuth reactor with the sCO2 Brayton cycle power generation system. It is a crucial element of the pressure boundary in the primary and secondary loop systems of the reactor, and its performance directly influences the efficiency and safety of the reactor's power generating system. In order to investigate the thermal–hydraulic performance of supercritical carbon dioxide and lead bismuth indifferent microchannel structures of PCHE, four sets of core plate physical models are established, in which the lead bismuth side adopts a straight channel, and the sCO2 side adopts straight channels, Z channels, and S-shaped channels, respectively. The flow and heat transfer properties of the heat exchanger are modelled using the commercial program ANSYS FLUENT. Comparative analysis of the numerical simulation results revealed that the heat transfer efficiency of plate-fin heat exchangers with Z-shaped and S-shaped channels surpasses that of straight channels. The Z-shaped channel has the highest resistance, followed by the 30° bend angle, which has stronger resistance than both the 15° bend angle Z-shaped channel and the S-shaped channel. The straight channel has the lowest resistance. Nevertheless, the L-S type flow channel demonstrates the most extraordinary comprehensive heat exchange performance. In the actual design process, it is necessary to comprehensively consider the thermal hydraulic performance, structural strength, and economic cost to select the optimal channel structure.