Abstract: The Taibei Depression is the main oil and gas bearing area of Tuha Basin, and the coal bearing stratum of the Xishanyao Formation is the most important source rock in the area. The sporo-pollen fossils from the well pu-1 and wel1 Caonan-l have been analyzed, identified and counted. The sporo-pollen fossils discovered from the Xishanyao Formation consist of 31 genera and 57 species. The assemblage is named as Cyathidites-Cycadopites-Quadraec-ulina based on their high percentages and stratigraphic significance. It is characterized by the slight dominance of gymnospermous pollen(51％). The pteridophyta spore amounts to 49％. The genera Cyathidites and Osmundacidites of the pteridophyta spores are predominant, their percentages amounting to 20％ and 13％ respectively. Gleicheniidites, Asseretospora and Deltoidospora are common, their percentages being 2-4％. Among gymnospermae pollen, the most abundant genera are Quadraeculina (17.5％ )and Cycadopites(13.3％). Moreover, Podocarpidites, Piceites and Classopollis are of higher percentage (3.5％, 5.5％ and 4.9％ in order). By analysing the geological distribution of main classes and important species and genera, comparing with the known assemblages which are of the same geologic age from the various districts in the world, and considering the conformable relationship of the Xishanyao Formation with the underlying late Early Jurassic Sangonghe Formation, the author thought that the assemblage of the Xishanyap Formation is similar to the ones from the Yanan Formation of Central Shanganning Basin, the Haifanggou Formation of Western Liaoning Province etc. The geologic age might be referred to early Middle Jurassic(Aalenian-Bajocian).