In order to realize wheelsets tread wear dynamic measurement,a tread wear dynamic measurement system based on laser image is established and the dynamic measurement method of the tread wear is investigated.Firstly,the two dimensional maximum correlation criterion image segmentation method based on quantum particles swarm optimization algorithm is used to image segmentation.Secondly,the thinning algorithm based on morphology combining with reptile tracking method was adopted to extract center line.Then,the space coordinate transformation algorithm based on polynomial combining with bilinear interpolation algorithm is used to correct the distortion curve.Fina1ly,the curve matching technique is used to match the standard curve and wear matching curve.The experimental results show that the measurement error is less than 0.2 mm and the measurement time is 2.1 s.It can meet the requirements of automatic measuring in the wheelsets maintaining factory.