A new algorithm method used to determine the correlation position between two marks for automatic alignment in microcircuit fabrication has been developed. This algorithm maintains the correlation technique advantage such as its high immunity to noise and poor contrast in the mark signal. The alignment overlay precision achieved is better than one pixel. By using this algorithm method, the 486‐33PC computer takes about 4 s to determine the correlation position without any special hardware. This article describes the method along with giving experimental results.