In　order　to　analyze　the　relationship　between　power　spectral　density(PSD)　method　and　international　roughness　index(IRI)　method　in　evaluating　road　roughness,　AR　model　was　adopted　to　simulate　road　roughness　condition　for　satisfying　PSD,　and　Newmark　β　method　was　employed　to　calculate　IRI　values,　the　relationship　formula　between　PSD　method　and　IRI　method　was　determined　by　using　least　square　method.　Analysis　result　shows　that　the　relationship　between　IRI　value　and　road　roughness　coefficient　meets　power　function,　and　to　correspond　to　IRI　values　in　quality　inspection　and　evaluation　standards　for　highway　engineering　(JTG　F80/1-2004),　a　＂very　good＂　item　of　road　roughness　evaluation　should　be　complemented　into　technical　specifications　of　maintenance　for　highway　(JTJ　073-96).　6　tabs,　10　figs,　20　refs.