In order to satisfy the requirements of detecting inner defects on mic ro-pipes extensively existing in the industry,a new approach based on importing external light source and exporting inner image is p resented.Optical information transmission components contain 360° panoramic conic mirror,sightpipe,ring illu minator,close shot optical lens and high resolution CCD camera,which construct the machine vision detection system toge ther wit h the computer.In the process of building the detecting system,posture adjustment of optical information transmission components is a k ey point which is deeply investigated.Evaluating basis of adjustment and complete implementation processes are given.Finally,the ideal micro-pipe inner defect measuring system is built.Based on the measuring system,the sample pipe with depth of 100mm and dia me ter of 9mm,which has simulated porosity defects of 0.5mm,0.8mm and 1.0mm on the internal surface is measured repeatedly,an d the RMS errors,are less than 0.025mm,0.026mm and 0.028mm,respectively.Experimental results show that based on the detect ing system built from the research of posture adjustment technology,the accurate alignment between the detecting components a nd the pipe and high-precision measurement for defects inside the micro-pipe c an be realized.