In this thesis, A novel method for measuring the evenness of raw silk is introduced. Firstly, the moving raw silk images are captured by image acquisition system including a Charge Coupled Device (CCD) line sensor, a telecentric lens, a light source. Then, the raw silk images are processed sequentially with threshold segmentation, morphological opening operation. Threshold segmentation is used to realize the separation of raw silk and background, morphological opening operation can eliminate the protrusion and the loop fiber which surrounding the main body of raw silk in the binary image. the coefficient of variation (CV value) of diameter is adopted to characterized the raw silk evenness. its suitable performance is illustrated using experimental results.