Nonlinear　pricing　originates　from　consumer　heterogeneity.　It　can　achieve　Pareto　improvement,　and　to　some　extents　it　can　avoid　fairness　disputes　of　price　discrimination.　The　authors　apply　a　consumer-parameter　model　on　explaining　the　use　of　the　non-linear　pricing　theory　in　the　intercity　passenger-dedicated　line　(PDL).　The　research　shows　that　the　success　of　using　nonlinear　pricing　in　PDL　lies　in　designing　prices　in　accordance　with　incremental　market.　Lower　prices　may　reduce　enterprise　revenue,　but　also　stimulate　customer＇s　consumption.　Nonlinear　pricing　can　restrain　the　lower　price　in　incremental　market　brought　by　low　prices,　and　thus　the　original　market　would　not　be　damaged,　finally　Pareto　improvement　can　be　achieved.　©　2010　ASCE.