Abstract: In the course of spinning,SCN(seed coat neps) whose proportion in nep is not large has a great effect on spinning quality.SCN quantity and size in the carding process were tested by using AFIS tester under following conditions, carding machine used different doffer,taker-in, speed and different types of taker-in, carding machine back sheet used stationary flat, web cleaner and carding segment. The experiment results show that carding machine can effectively get rid of SCN by 60 5%～81 4% in the carding process.The speed, type and production of taker-in have a little effect on SCN removal,while back stationary flat,carding segment and all kinds of suction units have little.