An effective design of a tungsten anti-scattering grid with 2 mm in thickness for medium-energy X-ray imaging is proposed. The grid is produced by precise mechanical drilling technology and is with the typical size of 52 mm × 52 mm. The flash radiographic experiments to test grid anti-scattering performance are performed based on a 450 kV medium-energy X-ray source, and the numerical simulation by the Monte Carlo method is also carried out. The imaging experimental results show that the image quality of flash radiography is improved substantially after the grid is used, and the boundary clarity in the sample core is enhanced obviously. The numerical simulation results indicate that scattering gray at any image position is lower than direct gray when the anti-scattering grid is used, and the ratio of scattering gray to direct gray is reduced by 74.7% compared to that without grids.