The Tongbomiao Formation is a significant reservoir and source of rock in the Hailar Basin. Determining its geological age, reconstructing paleovegetation, and paleoclimate is crucial for further research on this formation. Palynological identification data from 11 samples collected from 1738—2250 m depths in Well H5 of the northern Hongqi Sag in the Hailar Basin revealed the Pinaceae—Protoconiferus—Cicatricosisporites assemblage. This assemblage is characterized by the dominance of gymnosperm pollen, less fern spores, and absence of angiosperm pollen. Significant types of gymnosperm pollen include Pinaceae and Paleoconifer. Palynomorph types such as Protoconiferus, Pinuspollenites, Cedripites, and Perinopollenites play important roles in this assemblage. The presence of indicative pollen types like Cicatricosisporites, Fixisporites, Pilosisporites, Aequitriradites, Lygodiumsporites, Lygodioisporites, Kuylisporites, Exesipollenites, Jiaohepollis, and Erlianpollis, which have indicative geological age of the Tongbomiao Formation and facilitate comparison of palynological stratigraphy with adjacent areas. Based on palynological and Zr U–Pb data (130.3 ± 7.6—142.8 ± 2.0 Ma), the Tongbomiao Formation is determined to be from the Berriasian-Valanginian, possibly extending into the early Hauterivian. Research on paleovegetation and paleoclimate reconstruction shows that during the sedimentary period of the Tongbomiao Formation, there was a coniferous forest vegetation landscape and a semi-humid warm-cool climate, similar to today's warm temperate climate. Sporopollen fossils exhibit a brown color, with a sporopollen color index ranging from 2.99 to 3.04, indicating organic matter in a low-mature to mature stage, corresponding to a paleotemperature range of 60—135 ℃, suggesting that the formation is of significant for oil exploration and production.