Abstract: Abundant unicellular microfossils have been discovered in the stromatolitic cherts of Mid-Proterozoie Wumishan Formation (Sinian System) from western Hopei Province, China. These microfossils were critically studied in. petrographic thin sections of the cherts. K-Ar and U-Pb isotopes analyses give the age of Wumishan Formation approximate 1,300 millon years. These microfossils are well preserved in the siliceous matrix (chalcedony) in their natural state. Cellular microstructure of some microfossils are well preserved and is more complex in structure than any Precambrian procaryotic microfossils known to us. Some of cellular structures are similar to the nucleus or the organelles, which indicate that these microfossils are eucaryotic organisms. Some of the microfossils are apparently in the state of cell division, which shows that the cell division is perhaps not typical mitosis. The primary data in morphology of thes microorganisms and that of the infrared spectroscopic analyses of acid-resistant organic residues are given in this paper. Four new genera and seven new species are described, they are considered to be related to Rhodophyta.