The　behavior　of　clay　liner　at　the　bottom　of　landfill　site　plays　an　important　role　in　the　effective　performance　of　its　long-term　seepage　and　pollution　control.　In　view　of　the　high　saturation　state　of　soil　barrier　in　the　actual　yard,　the　liquid　phase　(pore　water)　and　gas　phase　(block　bubble)　are　considered　as　mixed　fluid　in　this　study.　By　establishing　soil　stress　equilibrium　equations,　mixed　fluid　mass　conservation　equations,　and　solute　mass　conservation　equations,　the　interaction　mechanism　of　soil　particle,　pore　fluid,　solute　is　considered　comprehensively;　and　a　hydraulic-　mechanical-chemical　fully　coupled　model　for　solute　transport　in　high　saturated　clay　liner　is　presented.　The　model　can　directly　and　accurately　solve　the　deformation　of　soil　layer,　mixed　fluid　pressure　and　solute　distribution　with　time　and　space.　The　multi-field　coupled　finite　element　analysis　software　COMSOL　is　used　to　carry　out　numerical　simulation　on　the　model;　the　results　show　that　the　model　results　are　in　good　agreement　with　the　results　obtained　by　Peters.　Meanwhile,　the　existence　of　compressible　gas　in　the　clay　liner　delayed　the　dissipation　of　the　excess　pore　fluid　pressure,　increased　the　settlement　of　the　soil　layer,　and　had　a　delayed　effect　on　solute　transport　in　the　clay　liner.　©　2018,　Science　Press.　All　right　reserved.