Abstract: In this work an anti-scatter grid with higher grid ratio was designed and fabricated based on our previous 2mm grid studies. To clarify the influence of grid thickness and phonon energy on scattering reduction, the acceptance solid angle of a single grid hole was analyzed carefully, where both blocked and unblocked ray were considered. A radiographic experiment and a Monte Carlo simulation were conducted to verify the performance of the grid. Results indicate the contrast of image was nearly doubled when a grid was used. Scatter rejection of the grid was estimated to be at least 1000∶1, which is high enough to suppress most of the scatterings in various application scenes. Results in this work would be helpful in improving the image property of the medium-energy radiography and could be supplied as a valuable reference when designing and fabricating an anti-scatter grid for high-energy flash radiography.