Abstract: On the basis of computer vision, a noncontact 3D measurement technology was proposed in this paper. Using neural network, the mapping relation between image point and special point was established. The projection of grating on object is regarded as matching features, with wavelet edge detection, searching non supervisor clustering and geometric invariance. Stereo precision matching is achieved at subpixel level. Furthermore, the multi scale and multi resolution attributes of wavelet are applied to image mosaic and data integration, so a large scale object can be measured. Experiments show that the technology has many advantages, such as simple equipment, fast speed and low cost, and that the measuring error is less than 0.5 mm/m.