Diameter measurement of animal fibres is one of the most important physical parameters to evaluate the quality of fibres. An automatic image analysis system for measurement of animal fibres is introduced in the article.The system is mainly based on the technology of image analysis as well as image recognition by computer

which can simultaneously achieve both the automatic diameter measurement and data statistic of many fibres. So all of the data are managed and useful curves are drawn after the rapid and simple measurement process with reliable and accurate results. The system has standard variance σ of 0.135

relative precision value δof 0.66%

and stability of long time of 0.112μm

reaching the advanced level in the world.