A method of correcting a layout pattern is provided in the present invention. The method includes the following steps. A layout pattern including at least two adjacent rectangular sub patterns is provided. The layout pattern is then input into a computer system. An optical proximity correction including a bevel correction is then performed. The bevel correction includes forming a bevel at a corner of at least one of the two adjacent rectangular sub patterns, wherein the bevel is formed by chopping the corner, and moving the bevel toward an interaction of two neighboring segments of the bevel if a distance between the bevel and the other rectangular sub pattern is larger than a minimum value. The angle between a surface of the bevel and a surface of the rectangular sub pattern is not rectangular. The layout pattern is output to a mask after the optical proximity correction.