The objective of this paper is to investigate the design of a forward-facing child restraint system (CRS) and related vehicle components through the study of three-year-old children in frontal impact. In this research, the finite element (FE) model of a five-point harness child restraint system was developed and a three-year-old Hybrid III dummy in MADYMO format was used along with the extended coupling method with LS-DYNA and MADYMO. This paper specifically addresses the parametric study of a five-point harness CRS and LATCH (lower anchors and tethers for children) system for forward-facing CRS in frontal crashes. The parameters include a chest clip, lower anchor straps and a seat pad. Furthermore, a new LATCH type is suggested, in which supplementary webbing was considered. The influence of preloading condition of a harness on a child dummy was explored as well. These results demonstrate the feasibility of the improved safety by devising an appropriate CRS.