This　study　was　conducted　to　investigate　the　groundwater　quality　features　of　the　Yongding　River　in　Beijing,　China,　and　its　relationship　with　urban　development　and　ecological　restoration　projects.　The　Yongding　River　has　been　cut　off　all　year　around　and　the　ecological　environment　has　continued　to　deteriorate.　Therefore,　a　series　of　river　ecological　restoration　projects　of　＇Five　Lakes　on　One　Route＇　have　been　implemented.　In　order　to　characterize　the　physico-chemical　properties　of　groundwater　and　evaluate　the　effects　of　these　projects　on　groundwater　quality,　by　using　principal　component　analysis,　this　study　analyzed　spatial　and　temporal　variation　on　the　basis　of　11　water　quality　parameters　at　10　monitoring　sites　of　＇Five　Lakes　on　One　Route＇　for　Yongding　River　during　April　and　September　of　2011　and　2016.　Principal　component　analysis　demonstrated　that　relatively　poor　groundwater　is　mainly　distributed　in　Fengtai　District　residential　and　industrial　land,　and　the　groundwater　in　Mentougou　District　woods　is　generally　better.　The　groundwater　quality　at　eight　monitoring　sites　kept　the　same　level　or　became　better,　and　the　construction　of　the　river　ecological　restoration　projects　of　＇Five　Lakes　on　One　Route＇　is　important　for　protecting　the　groundwater　resource.