To　simulate　the　transient　scalar　wave　propagation　in　a　two-dimensional　unbounded　waveguide,　an　explicit　finite　element　artificial　boundary　scheme　is　proposed,　which　couples　the　standard　dynamic　finite　element　method　for　complex　near　field　and　a　high-order　accurate　artificial　boundary　condition　(ABC)　for　simple　far　field.　An　exact　dynamic-stiffness　ABC　that　is　global　in　space　and　time　is　constructed.　A　temporal　localization　method　is　developed,　which　consists　of　the　rational　function　approximation　in　the　frequency　domain　and　the　auxiliary　variable　realization　into　time　domain.　This　method　is　applied　to　the　dynamic-stiffness　ABC　to　result　in　a　high-order　accurate　ABC　that　is　local　in　time　but　global　in　space.　By　discretizing　the　high-order　accurate　ABC　along　artificial　boundary　and　coupling　the　result　with　the　standard　lumped-mass　finite　element　equation　of　near　field,　a　coupled　dynamic　equation　is　obtained,　which　is　a　symmetric　system　of　purely　second-order　ordinary　differential　equations　in　time　with　the　diagonal　mass　and　non-diagonal　damping　matrices.　A　new　explicit　time　integration　algorithm　in　structural　dynamics　is　used　to　solve　this　equation.　Numerical　examples　are　given　to　demonstrate　the　effectiveness　of　the　proposed　scheme.　Copyright　(C)　2011　John　Wiley　&　Sons,　Ltd.