Considering　the　effects　of　the　rotation　of　the　principal　stresses,　time　effects,　and　wall-back　inclination,　a　new　solution　for　the　seismic　active　failure　angle　is　derived　by　the　pseudodynamic　method,　according　to　the　total　force　equilibrium　of　the　sliding　soil　mass.　Through　a　horizontal　differential　layer　method,　new　differential　equations　of　the　normal　seismic　active　earth　pressure　and　its　coefficient　for　an　inclined　rigid　retaining　wall　are　obtained　under　translation.　Then,　using　numerical　solutions　for　ordinary　differential　equations　based　on　the　Runge-Kutta　method,　influences　of　parameters　(i.e.,　the　vibration　period　time,　wall-back　inclination,　internal　friction　angle　of　backfill,　wall-soil　friction　angle,　height　of　wall,　amplitude　of　horizontal,　and　vertical　seismic　acceleration　coefficient)　on　the　seismic　active　failure　angle　are　discussed,　as　well　as　the　seismic　active　earth　pressure　and　its　coefficient.　Moreover,　the　seismic　active　earth　pressures　and　its　coefficients　calculated　by　proposed　method　are　compared　with　those　by　existing　pseudostatic　and　pseudodynamic　methods.　The　results　showed　that　the　seismic　active　failure　angle,　seismic　active　earth　pressure　and　its　coefficient　all　change　periodically　with　the　time,　and　the　distribution　of　seismic　active　earth　pressure　is　nonlinear　along　the　wall　height.　The　seismic　active　earth　pressure　and　its　coefficient　found　in　this　paper　are　larger　than　those　found　using　existing　pseudostatic　methods.　(C)　2018　American　Society　of　Civil　Engineers.