Line structured light scanning technology is extensively applied in three-dimensional (3D) reconstruction due to its advantages of having high precision and being non-contact. To quickly and accurately obtain the feature information of the light stripe center, a method of extraction and adaptive segmentation of the light stripe center is proposed for 3D measurement of structured light. First, a subpixel extraction method is presented to extract the light strip center; it quickly determines the normal direction of the light stripe and accurately extracts the light stripe center in the normal direction by employing the improved gray gravity method. Second, an adaptive contour segmentation method based on slope difference and dynamic neighborhood optimization is presented. Finally, the proposed method is adopted to measure the geometric size of the complex manufactured parts. The experimental results demonstrate that the maximum measurement error is 0.15 mm and the accuracy is <1  %  , indicating that the method is accurate enough to be applied to various kinds of measurements.