Abstract: In wool spinning, the determine of drawing gages for the series yarn production processes is based on wool cross length, and the drawing gages will have finally influences on the drawn sliver evenness. Therefore, it is critical important for yarn production technology to obtain wool cross length with high efficiency and precision. This paper, take the comb sorter test wool length as original data, on the base of theoretical analyze and logic reduction, digital wool length distribution array curve is obtained with Microsoft Office Excel. And through adding tendency curve， a high precision polynomial curve regression equation with relative ratio as high as 0.9940 is achieved， the deviation ratio of testing result is only 0.77% comparing with traditional manual length distribution method. To testing the wool cross length with digital method has advantages of convenient, speedy, precise and high efficiency.