Flatness detection method

The present invention discloses a flatness detection method. The system used by the method is formed by an imaging element, a display element, and an image processing element. Firstly, the imaging element is calibrated, then a reference plane is placed at a measurement position, a standard structure characteristic pattern is displayed in the display element and is projected to the reference plane, and the standard structure characteristic pattern is reflected and then is captured by the imaging element as a reference pattern. Then a detected plane is placed on a same position, the imaging element is used to capture the reflected pattern which is a measurement pattern. Through the comparative analysis of a measurement characteristic pattern and a reference standard pattern, combined with the structure parameter of a measurement system, the plane error distribution of the detected plane can be calculated. The flatness detection method has the advantages of high detection precision, low cost, convenience in use, and simple structure of the detection system and has a broad application prospect.