Abstract: Well preserved microfossils were here described from the middle of Hebiancun Formation, Hutuo Group, northern China, estimated to be 2,000 2,400 Ma years old based on the K-Ar and U-Pb isotopic. They were coccoids (Globophycuswenshanensis Xu sp. nov.) and filamentous (Siphonophycus cf. kestron and Siphonophycus sp.) and occur in petrographic thin sections. The coccoids were preserved by permineralization in the chert part of the conical stromatolites (Zhongtiaoshanella) and the filamentous in black chert. The paleoenviromental modal for the setting of the Hebiancun Formation was able to be reconstructed according to the microfossit assemblage and different lithology observed. The formation was divided in ascending orders as follows: The breccia; the thick sandy dolomite; the black chert in which the filamentous microfossils in subparalled colonies were preserved; and the dolomite with conical stromatolites in which the coccoidal microfossils with hyaline and unlamelleted sheath was observed. As mentioned above, it was conjectured that the descent and uplift of the geosynclinal area led to transgression and regression during the Hebiancun time. Compared with the all microfloras in the world known uptodate the characteristics of the microfossils from Hebiancun Formation was similar to that from Transvaal Supergroup, South Africa. Both of them show of the big sizeof the algal bodies inspite of different types. The algae Seemed to have a big cell period during their systematization.

Key words: Early Proterozoic, Hebiancun Formation, Globophycus, Siphonophycus Globophycus wenshanensis Xu sp. nov. (Plate 1, 1–5) Cells spheroidal or ellipsoidal, solitary, with hyaline, unlamelleted sheath, ce