This　paper　focuses　on　the　trajectory　optimization　problem　for　both　passenger　and　freight　trains　traveling　in　opposite　directions　on　a　single-track　railway　line.　Firstly,　we　formulate　a　trajectory　optimization　problem　that　aims　to　simultaneously　minimize　the　traction　energy　consumption　of　passenger　and　freight　trains,　as　well　as　the　total　travel　time　of　freight　trains.　Both　types　of　trains　are　subject　to　their　respective　operational　constraints,　such　as　safety,　punctuality　and　static　speed　limits.　Secondly,　we　transform　this　problem　into　a　multi-phase　optimal　control　problem　that　incorporates　the　timetable,　track　gradients,　speed　limits　and　signal　positions.　The　multi-phase　optimal　control　problem　is　then　solved　by　GPOPS-II　software.　Our　approach　enables　us　to　model　the　multi-tracks　at　stations,　allowing　trains　to　meet　and　overtake　at　stations.　Finally,　the　proposed　method　is　applied　to　case　studies　of　passenger　and　freight　trains　in　a　single-track　railway,　and　the　numerical　simulation　results　validate　the　effectiveness　of　the　proposed　method.　©　2024　SPIE.