Abstract: In order to reduce flow choking and the corresponding high drag force, an improved circular-arc grid-fin configuration is proposed in the present study. Compared to the conventional grid-fin configuration, the circular-arc layout decreases the length of the fin cell as to reduce the flow choking. Meanwhile, the circular-arc grid fins can be conveniently folded against the body so as to make them easier to store and transport. Viscous computational fluid dynamic simulations were performed to investigate flows over single grid fin. Comparisons of drag coefficients between circular-arc and sweptback grid fins indicate that both configurations have significant drag reduction under subsonic、transonic and supersonic than baseline grid fin configuration. However, when the flow velocity is above the third critical Mach number, the drag reduction of circular-arc grid fin is higher than that of sweptback grid fin. Through aerodynamic analysis of two different windward forms of circular-arc grid fins, it is clear that before the third critical Mach number, the lift coefficient of the convex plane windward model is much greater than the concave plane windward model (approximately 30%) and the baseline model, after the third critical Mach number the lift coefficient of the convex plane windward model and the baseline model tend to be consistent, while the concave plane windward model has a greater lift coefficient.