Nowadays, hard disk drives (HDDs) are widely used in portable consumer appliances and gadgets. These HODs are more susceptibl e to shock and vibration during using. Their shock performance under operation and non-operati on is becoming an increas ingly important iss ue. One important damage mode of the HOD is the " head slap" behaviour, which is triggered by a shock load th at exceeds th e suspension preload, causing the head to fl y off from the disk and then slap on the di sk. Thus, the particles generated on the disk med ium may cause contamination problem. The head slap should be stri ctl y avo ided. One approach for dea ling with the shock problems is to des ign a robust mechanica l system and slider/di sk interface. It is very clear that the trend of the HOD development is higher areal density and higher speed. The size of the HOD and its components become smaller and smaller. The improved perform ance of the mechanical parts has been of great sign ificance in thi s progress. A better understandin g of dynamic characteristi cs of the mechanica l parts is essenti al. To investigate the drop and impact dynamic characteristics of hard di sk dri ves, both experiments and numeri ca l simulations are conducted here. First ly, the boundary cond ition of disk of an HOD was in vestigated by finite element ana lysis and experimental tests. Modal analys is is conducted with simplifi ed FE model and the results are compared with experimental results. The rea l boundary cond ition of disk is simu lated with FE model considering the contact between clamp and disk and the contact between disk and hub. Based on the contact model , des ign