Abstract: Measuring diameters of cashmere is an important item for inspective and quarantine sections in exported cashmere.A new measuring method was put forward as follow. After the cashmere being magnified by a microscope,its image taken by a camera was transported to a computer connected with the camera. And then the image was displayed on screen of the computer by a image acquiring adapter in the computer. Firstly, the image (including background)was processed according to color value of their pixels. Secondly,the stains of background were filtrated by linear regression and intellective method. Thirdly, the irregular image was turned into regular image. Finally, caculating diameter of the regular image was conducted.