This paper puts forward a three-dimensional measurement system,which is composed by a line laser,an industrial camera,a stepper motor and computer.Describes its operating princip le is described,the geometric mathematical model is established,and a test platform is built.The centerline ex traction of structured light stripe based on gray square weighted centroid algorithm is proposed.The test results show that the accuracy of the centerline extraction method is sub-pixel level,and the system measuring error is less than ±0.03mm,which mee ts the needs of industrial applications.