The invention discloses a die-to-database (D2DB) contact window detection method which includes the steps of: 1) obtaining practical images of several contact windows in a wafer; 2) decoding the positions of the practical images to obtain a graphic file; 3) aligning the graphic file with a design database of a die; 4) performing image extraction to the practical images to obtain image outlines of the contact windows; and 5) measuring the different in key sizes between the image outlines of the contact windows and corresponding contact windows in the design database to obtain a contact window detection result of the wafer.