Method and system for determining QR code binary image is provided. Locating lines on which edges of the QR code locate are determined according to location information of locating points within the QR code image and distances between the locating points to edges of the QR code. Distances may be used to obtain locating lines on which edges of the QR code locate, with relatively smaller errors. When a QR code image is distorted, it generally bulges outward. The position of a determined locating line is within the interior of the QR code image, and an actual edge of the QR code partly overlaps with the locating line and partly locate on external side of locating line. Edge points on external side of a locating line are detected along the direction of the locating line and then are connected to form an edge line of QR code.