By　applying　computer　simulation　in　phase　contrast　imaging,　a　platform　for　the　design　of　imaging　system　and　research　of　imaging　theory　and　methods　could　be　provided.　A　new　simulation　algorithm　of　phase　contrast　imaging　based　on　X-ray　diffraction　theory　was　provided　using　ray　tracing　algorithm　in　computer　graphics.　Experiment　of　the　3D　simulation　of　Shepp-Logan　phantom　which　is　composed　of　ten　ellipsoids　with　different　in　both　shapes　and　materials　they　are　supposed　to　contain　was　made.　The　result　images　have　edge　enhanced　character.　The　opposite　experiments　show　that　the　images　produced　by　this　algorithm　are　highly　in　accord　with　real　physics　experiment.