The　driving　comfort,　which　is　mainly　determined　by　the　pavement　evenness,　is　one　of　the　most　important　indexes　for　evaluating　the　pavement　service　condition.　Current　evaluation　indexes　for　the　pavement　evenness,　such　as　the　international　roughness　index　(IRI),　are　mainly　determined　by　the　vibration　acceleration　method.　However,　the　driver　is　at　the　core　in　the　human-vehicle-road-environment　system.　Few　studies　have　focused　on　the　physiological　state　as　a　response　to　accelerations　induced　by　pavement　unevenness　and　evaluate　the　driving　comfort　on　this　basis.　In　this　study,　the　Root　Mean　Square　of　the　Successive　Differences　(RMSSD)　derived　from　the　driver＇s　heart　rate　variability　(HRV)　in　the　time　domain　and　was　selected　as　an　index　value　for　the　driver＇s　physiological　state.　Using　an　advanced　indoor　testing　platform,　the　RMSSD　values　of　five　drivers　were　recorded　by　a　KF2　electrocardiogram　tester.　The　relationship　between　the　RMSSD,　the　driving　speed　and　the　IRI　underwent　detailed　analyses.　The　results　of　the　tests　show　that　the　vertical　vibration　is　identical　when　the　drivers　are　driving　on　the　simulated　pavement　with　the　same　IRI　value;　however,　the　RMSSD　values　of　different　drivers　were　different,　i.e.,　the　perception　of　the　same　pavement　evenness　is　subjective.　Therefore,　when　evaluating　the　driving　comfort　based　on　the　pavement　evenness,　it　is　necessary　to　consider　the　physiological　index.　The　results　obtained　in　this　study　have　proven　the　feasibility　of　measurement　of　RMSSD　value　to　evaluate　the　pavement　evenness　and　driving　comfort.　They　are　therefore　a　powerful　augmentation　of　existing　evaluation　methods　and　also　provide　a　new　reference　for　further　optimization　of　the　pavement　surface　performance.