Surface defect is one of the most significant quality problems of cold-rolled strips,which are believed to be affected by rollers,rolling conditions,emulsion and annealing process.Therefore,identifying the influence of emulsion on strip surface quality correctly has critical importance of controlling strip surface defects.In this paper,topography and compositions of the strip surface defects,such as hot-strip scratch,stain,corrosion was analyzed to develop the judging method of emulsion causing surface defects.The corresponding countermeasures were proposed according to performances of emulsion,rolling,pickling,temper and annealing process.( 1 ) Lack of lubrication of the emulsion is the main reason for causing hot-strip scratch.The lubrication performances of emulsion should be improved from the aspects of emulsion concentration,temperature,additive content and so on.(2) The residue of emulsion,tempering liquid and residual acid to the surface of the strip led to appearance of spot and poor surface cleaning.The blow device should be improved to ensure the blowing residual emulsion.Concurrently,the reasonable annealing process and thermal volatilization of emulsion avoid spotting deposition caused by incomplete volatilization of emulsion.(3 ) The surface cleanliness of the cold-rolled strip is affected by the residuals on the strip surface,and finally,this paper proposes effective measures for improving the lubrication and detergency of emulsion by optimizing physical and chemical properties of the emulsion and strengthening management of emulsion.