One　challenge　in　evaluating　road,　transportation　and　environment　condition　to　match　with　drivers＇　credibility,　improving　the　road　safety　and　controlling　and　designing　＂humanization＂　of　safety　road　is　qualitative　standard　of　driver　workload,　which　is　expected　to　reduce　the　accident.　By　analyzing　mechanism　of　cognition　process　and　physiological　and　psychological　reaction　in　driving,　it　is　concluded　that　driver　workload　is　used　to　measure　driver　comfortableness　and　safety.　The　study　is　carried　out　in　simulative-cabin　(17　professional　drivers　drive　on　scenery　road　which　is　Class　II　highways　with　two-lane　about　20km　and　freedom　flow)　and　National　Highway　G109,　Mentougou,　Beijing　(6　drivers　drive　on　Class　II　highways　with　two-lane　about　20km　and　freedom　flow).　It　is　concluded　that　driver　workload　is　measured　by　heart　rate　and　pupil　size,　and　meanwhile　road　alignment　and　driver　comfortableness　have　inverse　correlativity　at　a　certain　speeds.　The　driver　workload　is　divided　into　three　grades:　comfortableness,　some　extent　tension　and　great　tension.　Analyzing　tested　data　by　regress　relativity,　difference　and　salience　in　groups,　it　is　obvious　difference　in　the　similar　highway　conditions　between　simulated-highway　and　real-highway,　which　driver　workload　in　real-highway　is　higher　than　in　simulation　and　the　revised　coefficient　of　driver　tension　in　simulation　is　1.2.　Finally,　the　conclusions　of　three　grades　controlling　criteria　of　pupil　size　are　obtained　to　evaluate　driver　workload.