Abstract: This article simulates the really running process of yarns during weaving by adopting CTT(constant tension transport) system to evaluate abrasion of yarns.Through mathematical method,it concludes that increasing guide speed and decreasing pre-tension are the effective measures to reduce the yarn-yarn and yarn-machine frictions.It is found that the yarns abrasion decreases by power and logarithm as the guide speed increases,while increases by index as the pre-tension increases.This conclusion has certain significance as guidance for weaving, especially for knitting.