The introduction of existing tire semifinished extrusion parts(TSEP) online detection methods and the analysis of advantages of point and line scanning method based on laser ranging technology are made. The system is mainly composed of twodimensional(2D) laser sensors, coordinated controller, industrial computer and the selfdeveloped software of data acquisition and process, analysis and recognition. Based on analysis of demand for TSEP and 2D laser sensor detection mechanism, a reasonable detection coordinate system is constructed, which can measure the TSEP contour size. At the maximum speed of 50 m/min and sampling frequency for 16 Hz, sampling distance can realize as low as 52 mm, width can be accurate to 0.5 mm and thickness can be accurate to 0.1 mm, which can meet the anticipation and thoroughly change the offline testing lag, preventing unqualified products from entering next procedure.