The Sinian system of northern China is well-developed in Yenliao region, especially in Chih County of Hopei, where one finds a complete stratigraphical sequence showing distinct contacts with both the overlying and underlying strata as well as rather clear subdivisions of three series and ten formations. It is considered the type section of the Sinian system of China.Since 1962 a systematic study of micro-flora (bacteria, algae and their spores) in Chih County of Hopei and in Penchsi County of eastern Liaotung has been carried on by the authors. A description of 7 genera, 33 species and 1 variety are new. The new genera named are Pseudozonosphaera gen. n., Dictyosphaera gen. n., Quadratimorpha gen. n., Triangumorpha gen. n., Polynucella gen. n., Polyporata gen. n. and Cornutosphaera gen. n.This study has revealed a regularity of vertical distribution of these microplant remains which is considered one of the criteria for the stratigraphic subdivision and correlation of the Sinian system. An attempt is made in correlating the Sinian type section in Chih County with its equivalent strata in other regions. It is indicated that the assemblage of mieroplant remains in the Chuanlingkou formation of the lower Sinian in Chih County bears resemblance to those in the lower and middle parts of the Riphean group of southern Urals and the Diabaig formation in the lower part of the Torridonian series of Scotland, while the assemblage of mieroplant remains in the Hsiamaling formation of the upper Sinian in Chih County is similar to that in the Vendian complex, especially its upper part, i.e., the Valdainian series of the Russian Platform.The relationship between the Sinian and Pre-sinian micropalaeo-flora and origin of combustible organic deposits is discussed. It is pointed out that sapromyxite, oil shale, oil and natural gas, all of great economic significance, could come into being in the Sinian period or at an even earlier time and that the Sinian strata may serve not only as reservoir rocks but also source beds of oil.During the Sinian the main elements of the organic world were bacteria and algae living in various water bodies. In the earlier part of the Sinian, there were Cyanophyseae in the main, while during late Sinian, Phaeophyceae developed rather exuberantly. No data available at present could confirm the idea that any advanced terrestrial flora had ever existed before the Cambrian.The method of micropalaeo-botanic analysis is proved to be useful for the studyof not only clastic but also chemical rocks such as limestone, dolomite and siliceous rocks. It is so far the only effective measure of palaeontology for settling the problem of subdivision and correlation of the Pre-cambrian strata.