Because the curvature mode used in dynamic detection is sensitive to the damaged location of the dynamic structure,the traditional method mainly used the central difference method to solve the curvature mode and its accuracy depends on the density of the measurement grid in dynamic detection,the central difference method will induce a very large error in dynamic damage detection.Taking advantage of the good approximation of the Chebyshev polynomial,we defined a Chebyshev polynomial function of the mode shape,and obtained the corresponding curvature mode by the second derivatives of the Chebyshev polynomial function of the mode shape. The method provided a reliable data for dynamic damage detection and achieved a good effect.