The　impact　of　the　incident　angle　of　earthquake　motion　on　the　seismic　response　of　the　long　lined　tunnels　is　studied.　Based　on　the　time-domain　finite　element　method　with　the　viscous-spring　artificial　boundary　condition,　the　earthquake　motion　of　oblique　incidence　is　transformed　into　the　equivalent　nodal　forces　acting　on　the　truncated　boundary　of　finite　element　model.　In　the　present　work,　the　formulas　of　equivalent　nodal　forces　for　the　plane　P　wave　with　arbitrary　incident　angle　are　deduced　and　implemented　into　the　commercial　software　abaqus.　The　effectiveness　of　the　formulas　and　its　implementation　are　demonstrated　by　two　numerical　examples　with　the　reference　solutions.　The　proposed　method　is　applied　to　investigate　the　seismic　responses　of　the　long　lined　tunnels　under　the　obliquely　incident　P　waves.　The　numerical　results　indicate　that　the　seismic　responses　of　the　long　lined　tunnels　are　highly　affected　by　the　incident　angles　of　P　waves.　Copyright　(c)　2016　John　Wiley　&　Sons,　Ltd.