Abstract: According to the size of circuit board is getting smaller, electronic components are getting more and more, qualicty requrements of circuit board are getting higher and highter, and be suitable for forquent confact inspection. This paper provides a solution to the no-wntact inspection for circuit boards based on computer image processing. The study mainly refers to image acquisition, processing and display of the results. Using TWAIN protocol circuit board image is obtained. According to RGB color space, the authors adopted the algorithm of image contour. Taking advantage of color space division, the components deletions and the components defelts are inspected. Compared with the traditional manual detection, the design has better efficiency for the inspection of components deletions and components defects.