Aiming at the problems of low extraction accuracy and weak anti-interference ability of line structure light centroids in turbid water bodies, this study proposes an improved internal advancement algorithm, which aims to enhance the accuracy and robustness of the extraction of line structure light centroids in complex environments. Firstly, the median filter is used to preprocess the image to suppress the noise, and combined with the eight-neighborhood method to quickly locate the starting point of the light stripe; subsequently, the grayscale neighborhood attribute method is introduced to dynamically estimate the pixel width of the current line of the line structured light, and based on this range, the maximum interclass variance method is applied to adaptively determine the binarized threshold value, which effectively reduces the background interference; finally, the grayscale gravity method is used to calculate the initial centroid in the constrained range of pixel widths and use this as the basis to advance upward and downward to search for the center point of the line structured light. Comparison tests are conducted in various turbid water environments and different structured light patterns. The results show that compared with the original internal advancement algorithm, the root mean square error of the improved algorithm is reduced by 13.33%, and the running speed of the algorithm is increased by 69.07% compared with Steger’s algorithm, thus realizes the balance between accuracy and speed.