The　cyclic　wetting-drying　(W-D)　phenomenon,　which　is　a　part　of　weathering　processes,　plays　a　vitally　important　role　in　affecting　rock　materials＇　properties.　In　this　paper,　the　gypsum　breccia,　an　environmentally　sensitive　rock,　was　taken　as　the　research　object,　which　has　the　characteristics　of　high　solubility.　The　deterioration　behavior　of　gypsum　breccia　under　W-D　cycles　with　different　flow　rates　was　investigated.　A　one-dimensional　water　saturation　test　was　conducted　to　study　the　coupling　mechanism　of　water　saturation-dissolution　of　gypsum　breccia.　A　series　of　W-D　cycle　tests　with　different　flow　rates　(0,　10,　and　20　l/h)　for　gypsum　breccia　were　conducted　to　reveal　its　deterioration　behavior.　Furthermore,　the　influence　of　these　effects　on　the　stability　of　the　tunnel　was　discussed.　The　results　show　that　gypsum　breccia　has　a　coupling　behavior　of　water　saturation　and　dissolution　in　the　water　environment.　The　effect　of　W-D　cycles　is　the　primary　reason　for　the　formation　of　visible　cracks　in　gypsum　breccia,　while　the　flowing　water　will　wash　away　the　loose　particles　caused　by　the　action　of　W-D　cycles　and　accelerate　the　development　of　visible　cracks　and　dissolution　in　gypsum　breccia.　The　combination　of　these　two　actions　gradually　deteriorates　the　self-stability　of　the　surrounding　rock,　which　eventually　leads　to　lining　damage　due　to　overload.　The　study　can　provide　references　for　the　engineering　design　of　tunnels　in　gypsum　breccia.