The　conventional　method　of　determining　rock　mechanical　parameters　now　can　only　obtain　the　overall　strength　of　the　rock;　while　in　the　weathered　layer　of　ancient　buildings　rock　constructional　elements,　of　which　the　mechanical　parameters　gradually　change.　It　is　not　enough　to　study　the　stability　and　durability　of　rock　ancient　buildings.　So　a　method　with　integrated　use　of　on-site　sonic　CT　test,　surface　rebound　and　laboratory　test　to　obtain　the　mechanical　parameters　of　rock　constructional　elements　is　proposed.　The　method　is　put　into　action　as　follows.　The　longitudinal　wave　velocity　distributions　along　the　depth　profile　in　the　rock　constructional　elements　are　acquired　by　the　on-site　sonic　CT　test.　The　statistical　relation　of　the　mechanical　parameters　and　wave　velocity　is　obtained　by　selecting　rock　on-site　that　analogous　to　the　rock　constructional　element　studied　to　do　the　indoor　mechanical　tests　and　the　wave　velocity　test.　The　mechanical　parameters　distribution　along　the　depth　profile　in　the　rock　constructional　elements　is　derived　by　combining　the　outcomes　mentioned　above;　based　on　this,　the　relationship　between　mechanical　parameters　and　depth　within　the　weathered　layer　is　analyzed.　The　relationship　between　the　surface　compressive　strength　ratio　and　the　weathered　depth　is　derived　by　weathered　depth　studying　and　surface　rebound　test　on　the　typical　rock　constructional　element　in　different　weathering　zones.　This　method　is　systematically　introduced　in　this　paper　with　the　example　of　Guyue　Bridge　in　Yiwu　built　in　the　Song　Dynasty.　This　paper　studied　the　relationship　between　mechanical　parameters　and　depth　within　the　weathered　layer　and　the　relationship　between　surface　strength　of　rock　constructional　element　and　weathered　depth　of　weathered　rock　constructional　element　which　were　in　the　bearing　structure　of　the　Song　Dynasty　Guyue　Bridge　in　Yiwu.　The　studies　show　that:　in　the　bearing　block　stone　of　the　Song　Dynasty　Guyue　Bridge,　the　compressive　strength　ratio　and　the　elastic　modulus　ratio　vary　negative-exponentially　with　the　depth　in　weathered　layer;　the　relationship　between　compressive　strength　ratio　of　surface　and　weathered　depth　conforms　to　the　two　order　polynomial.