Centerline extraction of structured light stripe is the key step of topography measurement. The centerline extraction of structured light stripe based on the principal component analysis is proposed. Otsu′ s method is used to extract the region of interest (ROI) area of image. After twice Gaussian convolution, the gradient distribution of the ROI area is got, then the rough position of the stripe center is obtained based on the gradient distribution. Using principal component analysis the normal vector is obtained. Based on the rough position of the stripe center, the center of structured light stripe can be found in normal directions with second order Taylor series expansion of grayscale distribution function. The experimental results show that the algorithm has higher speed and precision characteristics. Compared with Steger algorithm, the mean square error (MSE) is less than 0.003 pixel, and it is nearly three times as fast as Steger algorithm. This method can realize the rapid and high precision extraction of structured light stripe, and lays a foundation of real-time application for structure light vision detecting.