An identifying system is provided for identifying a geometrical element in an image automatically. The image may be retrieved from an image capturing apparatus and is imported in a coordinate system. The identifying system includes: a collecting module for collecting dots from the image as a dot muster and retrieving coordinates of all dots of the dot muster from the coordinate system; a curve fitting and geometrical element identifying module for curve fitting according to the coordinates of all the dots of the dot muster to identify what geometrical element the dot muster is; a storing module for storing the coordinates of all the dots of the dot muster, data produced during the curve fitting process, and result data of curve fitting and geometrical element identifying; and an outputting module for outputting the result data. A related identifying method is also provided.