River　valley　terrain　can　lead　to　local　amplification　effects　of　site　seismic　responses　and　significant　spatial　variation　of　strong　ground　motions.　This　paper　presented　a　semi-analytical　solution　for　the　scattering　of　incident　plane　P-waves　by　a　saturated　river　valley　with　arbitrary　shapes　containing　water,　using　the　moment　method　and　the　wave　function　expansion　method.　The　influence　of　factors　such　as　valley　geometry　shapes,　soil　porosity,　wave　incident　angle　and　frequency　on　the　seismic　response　of　valley　topography　is　further　investigated.　Parameter　analysis　shows　that　these　factors　have　a　significant　impact　on　the　site　seismic　response.　Soil　porosity　has　a　greater　impact　on　the　horizontal　response　of　the　site　than　on　the　vertical　response.　Moreover,　the　soil　porosity　is　directly　related　to　the　amplitude　of　the　pore　pressure,　while　the　incidence　angle　and　frequency　of　the　incident　wave　determine　the　distribution　position　of　the　pore　pressure　amplitude.　This　semi-analytical　solution　can　be　seen　as　an　attempt　to　solve　the　scattering　problem　of　incident　P　wave　by　saturated　river　valleys　of　arbitrary　shapes　containing　water.　The　purpose　of　this　paper　is　to　provide　a　reference　and　a　possible　way　for　subsequent　scholars　to　study　the　analytical　solution　to　this　problem.　The　conclusions　drawn　from　the　parameter　analysis　in　this　paper　can　also　serve　as　a　theoretical　basis　for　seismic　fortification　in　saturated　valley　areas.