Abstract: In the design of the open grid gas-cooled space reactor core, the helical wires are used on the fuel rods, which will have great influence on the flow and heat transfer characteristics of the working mass. In this paper, the CFD method was used to analyze the flow and heat transfer characteristics of He-Xe gas mixture in an annulus wrapped with a helical wire and the import and export parameters spatial distributions such as temperature, pressure, flow rate and fluid density were obtained. The results show that the introduction of helical wire greatly increases the Fanning friction factor, and some helical wire structures will reduce the Nusselt number by 20%-30%. Moreover, the thermal-hydraulic performance ratios of the five helical wire structures studied in this paper are all less than 1. The research results are of great significance to the thermal design of gas-cooled space reactor core and to improve the safety of the system.