The geochemical study on well Songkeace prefix = ns0 ns = "urn:schemas-microsoft-com:office:smarttags" />cnv>cnv ns1:UnitName="in" ns1:SourceValue="1" ns1:HasSpace="True" ns1:Negative="True" ns1:NumberType="1" ns1:TCSC="0">ace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />cnv w:st="on" TCSC="0" NumberType="1" Negative="True" HasSpace="True" SourceValue="1" UnitName="in">-1 incnv>cnv>cnv> aceName>aceName>aceName w:st="on">SongliaoaceName>aceName>aceName> aceType>aceType>aceType w:st="on">BasinaceType>aceType>aceType> indicates the biological development, varied water environments and paleoproductivity of ace>aceName>ace>aceName>ace w:st="on">aceName w:st="on">paleo-SongliaoaceName>aceName>ace>ace>aceName>ace> aceType>aceType>aceType w:st="on">LakeaceType>aceType>aceType> during the Late Cretaceous. The results show that the highest paleoproductivity achieved at 3 cnv>000 gcnv>/(m²·a) during the deposition of the 1st Member of Qingshankou Formation (K2qn1) and the 1st Member of Nenjiang Formation (K2n1). During the early age of Qingshankou 2nd-3rd Members’ deposit, the nutrients of the lake decreased to mesotrophic-eutrophic. In the late age of Qingshankou 2nd-3rd Members’ deposit, the bioproductivity bloomed again and the lake became mesotrophic. The lake was in mesotrophic state during the deposit of Yaojia 1st Member. Both in the early and late deposit of Yaojia 2nd-3rd Members, the lake was in oligotrophic state and in the mid stage of deposit the lake became mesotrophic with increasing bioproductivity. It is concluded that the paleolake was characterized with blooming biomass and vibrating water environment.