Abstract: Taking cold rolled strip as the research object, the influence of surface state of cold rolled strip on the accuracy of roughness measurement was studied. The results show that the strip surface cleanliness had a great influence on the roughness measurement results, and the strip surface need to be wiped with alcohol before measurement. The strip surface scratch also had a great influence on the roughness measurement results. The intermediate sampling process should be controlled to reduce the risk of scratch, so as to improve the accuracy of roughness measurement.