The　size-dependent　elastodynamic　plane　problems　are　described　by　a　consistent　couple-stress　theory　(C-CST)　in　this　paper.　The　time-domain　basic　equations　are　then　transformed　to　frequency　domain　by　the　Laplace　transform　method.　The　Laplace-domain　boundary　integral　equations　(BIEs)　together　with　the　fundamental　solutions　are　derived.　Then,　these　BIEs　are　numerically　solved　by　a　collocation　method　in　conjunction　with　the　numerical　treatment　of　singular　integrals.　The　time-dependent　solutions　are　obtained　by　the　Durbin＇s　method　for　the　inverse　Laplace-transform.　Some　typical　size-dependent　elastodynamic　problems　are　numerically　studied　by　the　developed　boundary　element　method　(BEM).　Good　agreements　are　observed　between　the　present　results　and　the　corresponding　analytical　or　numerical　solutions,　which　validates　the　high　accuracy　of　the　present　BEM.