The　sustainable　intensification　(SI)　of　cultivated　land　use　(CLU)　is　important　for　achieving　global　sustainable　development　goals　(SDGs).　However,　in　the　rapid　advancement　of　agglomeration　economies,　it　remains　unclear　whether　economic　agglomeration　(EA)　affects　SI.　Combined　with　emergy　theory,　this　study　utilized　socioeconomic　and　natural　environment　data　from　31　provincial　administrative　regions　from　1990　to　2017　to　evaluate　the　SI　level　in　China.　It　further　analyzed　the　impact　of　EA　on　SI　using　a　spatial　econometric　model　that　includes　mediating　effects.　The　results　showed　that　the　EA　level　in　China　continued　to　rise,　whereas　the　SI　level　continued　to　decline　from　1990　to　2017.　The　mediating　effect　analysis　showed　that　fiscal　support　for　agriculture　and　agricultural　labor　productivity　have　a　suppression　effect　of　|-　4.186|%　and　|-　2.002|%　in　the　local　region,　while　cultivated　land-use　intensity　has　partial　mediation　of　6.350%　in　the　local　region;　and　agricultural　labor　productivity　has　a　suppression　effect　of　|-　4.680|%　on　the　surrounding　region,　while　cultivated　land-use　intensity　has　stronger　partial　mediation　relative　to　the　local　region,　even　up　to　10.402%　on　surrounding　regions.　This　implies　that　the　impact　of　EA　on　SI　involves　complex　paths　and　spatial　differences.　This　study　provides　a　better　understanding　of　the　reasons　for　the　continuous　decline　in　the　SI　in　agglomeration-type　economic　development　and　feasible　policy　proposals.