A new method of the defect measurement is proposed by use of rotating aperture-stroboscopic speckle interferometry. The advantage of this method is that it is a non-contact measurement, not affected by form or place of the defect, and can accurately measure the size and form of the defect. Principle of rotating aperture-stroboscopic speckle interferometry and its application in defect detect and measurement are proposed. By using the method, defect and its size can be easily detected and measured in spite of the shape and position. The analytic formulas of average intensity of light and experimental result are given．Both theoretical analysis and experimental result show that a single specklegram can accommodate adequate information to replay the whole dynamic process of an object. During the process of replaying dynamic object, the position of defect doesnot change with the strip of speckle photograph by use of rotating filter aperture.