To investigate the impact of magnetic heads on disk in a hard disk drive, an elastic-plastic contact model for rough sphere contacting rigid flat in slip contact condition is provided. The normal load and the real contact area as functions of separation and plasticity index for the rough spherical elastic-plastic contact are investigated by mathematical modeling and MATLAB simulating. The results are compared with the perfect smooth spherical contact model, CEB (Chang-Etsion-Bogy) model and CKE (Cohen-Kligerman-Etsion) model in stick contact condition for different values of the plasticity index. It is shown that the normal load and real contact area of present model are more accurate than that of the CEB and CKE models. This is because the CEB and CKE models neglect the elastic-plastic contact and fully plastic of a single asperity, respectively, resulting in the limitation for the analysis.