The lifting performance of grid fins with different grid sections was also different. Early research showed that the diamondshaped section and the four angle section grid fins had better drag reduction ability than the rectangular section grid fins. Based on that, the grid fin with 45 degree sweepback was studied by numerical simulation. Results showed that three types of quadrilateral sweptback grid fins and its positive set were able to effectively improve the lift and increase the lift drag ratio. And the aerodynamic characteristics of the diamond-shaped section and four angular section sweptback grid fins were better than the rectangular section sweptback grid fins.