The　monotonic　axial　compression　test　was　performed　on　ten　groups　of　short　columns　confined　with　circular　hoops　to　investigate　the　size　effect　of　the　mechanical　properties　of　confined　concrete　under　axial　compressive　loading.　Based　on　the　result　of　the　experiment,　the　failure　characteristic,　ultimate　strength　and　deformation　capacities　of　various　specimens　were　comparatively　analyzed.　The　test　result　shows　that:　(1)　As　the　size　of　the　specimen　increases,　the　peak　strength　decreases,　and　the　lower　the　volumetric　ratio,　the　more　obvious　the　decreasing　trend.　(2)　As　the　size　of　the　specimen　without　concrete　cover　increases,　the　axial　strain,　the　hoop　strain　and　the　ductility　become　weaker.　(3)　The　ultimate　strength　of　the　specimen　with　lower　volumetric　ratio　of　transverse　reinforcement　increases　due　to　the　existence　of　the　concrete　cover,　and　the　strength　of　the　specimen　with　bigger　size　increases　more.　When　the　volumetric　ratio　of　transverse　reinforcement　is　high,　the　contribution　of　the　concrete　cover　on　the　ultimate　strength　of　the　specimens　is　very　little.