Abstract: The influence of the source out of the focused grid on the image in high-energy X-ray radiography is studied by theoretic analysis and numerical simulation. Direct radiation loss fractions under the conditions, such as the lateral decentering, the inclination and the source out of the focused distance, are calculated by analysis. Direct radiation loss fraction under grid manufacture by the stack of foil sheets is obtained. The theoretical results are validated using Monte Carlo code. The results show that the conditions of the grid out of focus toward the source and grid manufacture by the stack of foil sheets are equivalent to devalue the hole diameter, meanwhile the transmission inside the hole is held the line.