Abstract: Cold deformation was done on CSP rolled SPHD steel sampling sheets by duo mill,then.the tensile strength and rate of elogation were measured by tension experiment machine,the situation of work-hardening was analysed,and the rolling direction cross-section metallurgical structure of the sheets under different deformation was analysed.The result shows that after cold deformation,the steel tensile strength increases and rate of elogation decreases,the variation of tensile strength increases when deformation increases,work-hardening is very obvious.The cross-section grain in rolling direction becomes refined when deformation increases.