Based　on　the　model　of　the　driver＇s　process　of　collecting　and　dealing　with　information　of　free-flow　passenger　cars　on　freeway,　this　article　explores　the　factors　and　corresponding　rules,　which　affected　speed　on　a　horizontal　curve.　A　two-step　model　using　the　statistical　method　was　developed　for　prediction　of　operating　speed　on　horizontal　curve　with　different　joint　alignments.　Compared　with　the　result　of　field　data　and　the　prediction　of　the　Australia　model,　the　two-step　model　has　the　merit　of　high　prediction　accuracy　with　the　85th-percentile　operating　speed.　The　model　could　be　applied　widely　in　the　alignment　design　approach　of　operating　speed　and　traffic　simulation.