The　current　study　explores　how　tourism　mental　fatigue　influences　tourist　citizenship　behavior　by　examining　a　moderated　mediation　model.　The　results　indicate　that　tourism　mental　fatigue　negatively　influences　tourist　citizenship　behavior,　and　this　relationship　is　mediated　by　psychological　contract　breach.　Additionally,　the　relationship　between　motivational　fatigue　and　psychological　contract　breach　and　the　indirect　link　between　motivational　fatigue　and　tourist　citizenship　behavior　are　weaker　for　tourists　with　higher　internal　service　locus　of　control.　Thus,　in　promoting　tourist　citizenship　behavior,　DMOs　should　develop　strategies　to　reduce　tourism　mental　fatigue,　and　pay　attention　to　tourists＇　psychological　contract　and　service　locus　of　control.