To achieve the optimal design of zigzag printed circuit heat exchanger (PCHE) in the supercritical carbon dioxide gas-cooled reactor nuclear power system, the influence of the turning angle on the flow and heat transfer characteristics of carbon dioxide in PCHEs was studied by numerical simulation, and the correlations for Fanning friction factor and Nusselt number calculation were obtained. The thermal resistance of the heat transfer process was analyzed, and the comprehensive performance of the heat exchanger was discussed. The results show that the Fanning friction factor and convective heat transfer coefficient both increase parabolically with the increase of the turning angle, and the growth is relatively slow when the turning angle is less than 20°. The thermal conduction resistance accounts for 4.16% ~ 16.02% of the overall thermal resistance, and it increases with the increase of the mass flow rate and the turning angle. It should not be ignored in the heat transfer calculation of printed circuit heat exchanger. With the increase of the turning angle, the increase of the Nusselt number is smaller than that of the Fanning friction factor. The pumping power for transferring the same heat increases, but the required heat exchange area decreases. The manufacturing cost are reduced, and in practical applications, further techno-economic analysis is required to select the optimal turning angle. To control the proportion of the flow resistance in the channel to the inlet pressure, the turning angle should not exceed 20°.