Using three-dimensional (3D) measurement technology with linear structured light, the total 3D morphology of a workpiece can be reconstructed with continuous multi-frame contours that are adjacent. To improve the extraction speed of the centerline, a fast extraction method of stripe center based on time-continuous frame information multiplexing is proposed in this paper, which is in view of the similarity between continuous frame images. First, the centerline coordinates of the first frame laser stripe are calculated using the adaptive gravity-center extraction algorithm using stripe segmentation. Second, based on the centerline coordinate information of the previous frame, the rough location of stripe in the current frame image can be calculated quickly. Finally, the sub-pixel calculation on the centerline of the stripe is performed. According to the image similarity of time-continuous frames, the method multiplexes the centerline coordinate information to reduce repeated calculation, which can improve the algorithm speed effectively. The experimental results show that the method can achieve the centerline calculation with a higher speed of up to 133 frame/s, which greatly improves the 3D scanning speed with linear structured light and can be applied to other 3D reconstructions of large workpieces.