This　paper　presents　a　systematic　experimental　investigation　to　evaluate　the　effect　of　the　initial　damage　degree　on　static　and　dynamic　compressive/splitting-tensile　failure　behaviors　of　concrete　cubes　with　various　structural　sizes.　The　experimental　parameters　involve　three　initial　compressive　damage　degrees　(0%Pmax,s,　40%Pmax,s,　and　80%Pmax,s),　two　loading　strain　rates　(epsilon　=　10-5/s　and　10-2/s),　and　five　geometric　dimensions　(side　length　75,　100,　150,　200,　and　300　mm).　Test　results　indicate　that　as　the　initial　damage　degree　increases,　both　static　and　dynamic　nominal　strength　are　reduced.　The　influence　of　initial　damage　degree　on　dynamic　failure　strength　is　more　significant　than　that　on　static　strength.　Compared　to　dynamic　compressive　strength,　the　initial　damage　de-gree　has　a　more　significant　influence　on　dynamic　splitting　tensile　strength.　The　influence　of　geometric　dimension　on　nominal　strength　is　weakened　with　the　increasing　loading　strain　rate.　The　increasing　initial　damage　can　enhance　the　influence　of　geometric　dimension　on　nominal　strength,　resulting　in　a　more　obvious　size-effect.