Abstract: In order to study the image analysis method suitable for the sectional detection system based on high power semiconductor line-laser, several threshold algorithms were proposed to process and analyze the light-stripe images. An outdoor platform was built to simulate large-visual-angle laser projection, then images were collected by CMOS camera. Three threshold algorithms were introduced to analyze the images,and the center position of the light stripe was extracted by barycenter method, then advantages and disadvantages of the algorithms were compared. Results showed that the improved Otsu method could obtain a good performance. Besides,after considering signal-to-noise ratio, the character of objects and line-laser itself, the common applicable conditions of the algorithm were proposed under the line-laser system.