The analysis of a spar platform in deep water using a time domain approach is presented. A comparative study is performed against experimentally available data to validate the numerical model. Investigations were made for three different kinds of waves, i.e., monochromatic, bichromatic and irregular. In general good agreement was achieved between experimental and analytical results. After validated the numerical model, parametric studies were conducted to evaluate their influences on spar’s behavior. These studies include; the number of waves used in JONSWAP spectrum, deformed versus original geometry equilibrium (original geometry), current velocity and modeling with and without mooring lines.