This study applies DE (discrete element) computational method to the dynamic problems of a vibrating string. The DE method was originally initiated to analyze granular materials and now it has expanded to model fabric dynamics which is of interest in a number of applications including those that manufacture or handle textiles, garments, and composite materials. Owing to the complex interactions between each discrete element, simple circular geometric rigid model has been used in the conventional DE method. However, in order to analyze the slender shape and flexibility of materials such as fabrics or strings, longer and flexible geometric models, named as fiber models, was developed. The fiber model treats a series of connected circular particles, and further can be classified as being either a RF (rigid fiber) or a CFF (completely flexible fiber) model. To check the feasibility of those models, dynamic problems were solved and it is found that the fiber models accurately simulate the dynamic and vibration behaviors of horizontally or vertically placed strings.