In　order　to　protect　Chinese　ancient　buildings,a　Qing　Dynasty　building　in　Sichuan　province　was　taken　as　example　to　study　its　aseismic　characters　after　strengthened.　By　ANSYS　program,semi-rigid　character　of　tenon-mortise　joint　as　well　as　contact　between　wooden　constitution　and　walls　were　simulated.　Then　by　modal　analysis　basic　frequency　as　well　as　main　modes　of　the　structure　were　obtained;By　response　spectrum　analysis　inner　forces　as　well　as　displacements　of　the　structure　under　7-degree　intensity　of　seldomly　occurred　earthquakes　were　obtained.　Results　show　that　after　strengthened,main　modes　of　the　structure　are　of　translation;Under　7-degree　intensity　of　seldomly　occurred　earthquakes　peak　values　of　displacement　as　well　as　inner　forces　of　the　strengthened　building　are　all　within　permissible　scopes,which　proves　its　good　aseismic　characters.