1. Institute of Exploration and Development, Daqing Oilfield Company Ltd., Daqing 163712, Heilongjiang, China;
2. Key Laboratory for Evolution of Past Life and Environment in Northeast Asian(Jilin University), Ministry of Education, Changchun 130026, China;
3. Yuhua Highway Engineering of Jilin Province Company Ltd., Changchun 130062, China

Based on the palynological data from 1 226.0~1 538.0 m of Dongji 3 borehole, the Cyathidites-Taxodiaceaepolleni-Aquilapollenites assemblage is established for the Upper Cretaceous in Sanjiang Basin, eastern Heilongjiang. The assemblage is characterized by abundant gymnosperm pollen (48.10%~78.58%), fern spores (2.44%~34.18%) and angiosperm pollen (0%~28.26%).Fern spores mainly consist of Cyathidites (0.79%~37.50%), Cicatricosisporites (0%~12.50%) and Leiotriletes (0%~10.00%). Important spores are Appendicisporites, Schizaeoisporites, Lygodiumsporites and Lygodioisporites.Among the gymnosperm pollen, Inaperturopllenites (11.29%~38.83%) and Taxodiaceaepollenites (12.66%~28.57%) are dominant, followed by Tsugaepollenites, Parcisporites, Parvisaccites, Ephedripites and Classopollis. The angiosperm pollen is characterized by high content of Tricolpites (0%~16.46%) and Betulaepollenites (0%~15.22%), followed by Momipites and Tricolporopollenites, with Aquilapollenites, Fibulapollis and Proteacidites as important components. The assemblage can be closely correlated to the palynological assemblage from Nenjiang Formation in Songliao Basin, with an age of Santonian-Campanian. In view of the conchostracan fauna represented by Estherites mitsuishii, E. liuxinensis, Tylestheria cf. shanhoensis, Halysestheria yui, Calestherites sp. and Brachygrapta? sp. was found in the Hailang Formation in the outcrops at Nantuanshanzi and Gaojia villages in Ning'an City, eastern Heilongjiang, and the fauna is also common in the Nenjiang Formation in Songliao Basin, the strata at depth 1 226.0~1 538.0 m in Dongji 3 borehole should be assigned to Hailang Formation. Therefore, the former Qixinghe Formation should be abandoned.