Different　from　the　current　mainstream　research　on　quasi-static　size　effect,　this　paper　studies　the　size　effect　of　seismic　dynamic　damage　of　RC　compression-bending　members,　and　comprehensively　analyses　the　influence　of　dynamic　loading　and　size　effect　on　the　bearing　capacity　and　other　mechanical　properties　of　RC　compression-bending　members.　Three　different　sizes　of　RC　columns　with　rectangular　cross-section　are　prepared　according　to　the　similarity　relationship.　Large　eccentricity　loading　are　carried　out　according　to　the　eccentricity　of　0.6h0.　Three　loading　rates　are　adopted　in　the　loading　scheme,　and　seismic　action　is　discussed　by　dynamic　loading.　The　test　results　show　that　the　bearing　capacity　of　the　specimens　increases　with　the　increase　in　size,　but　the　safety　factor　of　bearing　capacity　decreases　and　the　nominal　stress　decreases.　Meanwhile,　the　peak　and　ultimate　strain　of　the　tensional　steel　bar　and　the　compressive　concrete　decrease　with　the　increase　in　size.　Contrary　to　the　rule　of　size　effect,　nominal　stress,　safety　factor　of　bearing　capacity,　strain　of　tensional　steel　bar　and　compressive　concrete　increase　with　the　increase　of　loading　rate.　©　2020,　The　Editorial　Board　of　Journal　of　Basic　Science　and　Engineering.　All　right　reserved.