Abstract: This paper presents the residual stress states of circular saws measured by an X-ray diffractometer. The residual stresses of no-tensioned, tensioned and lost tensioned circular sawblades were measured and analyzed. The results show that the tangential residual stress is tensile and the radial residual stress is compressive in the exterior loop of the tensioned region; both of the tangential and the radial residual stresses are compressive in the inner loop of the tensioned region in the tensioned circular saw blades. The tangential and the radial residual stresses are both compressive in the no-tensioned and the lost tensioned saw blades. In the case where bearings of the incident X-ray beam are not in the radial direction, the φ splitting is apparent on the surfaces of circular sawblades. At the depth of 20-30 μm, the φ splitting is not significant.