A semiconductor processing method is provided and includes the following steps. A first semiconductor process is performed for a wafer to obtain plural overlay datum (x, y), wherein x and y are respectively shift values in X-direction and Y-direction. Next, A re-correct process is performed by a computer, wherein the re-correct process comprises: (a) providing an overlay tolerance value (A, B) and an original out of specification value (OOS %), wherein A and B are respectively predetermined tolerance values in X-direction and Y-direction; (b) providing at least a k value (kx, ky); (c) modifying the overlay datum (x, y) according to the k value (kx, ky) to obtain at least a revised overlay datum (x′, y′); and (d) calculating a process parameter from the revised overlay datum (x′, y′). Lastly, a second semiconductor process is performed according to the process parameter . . . . The present invention further provides a lithography system.