This paper deals with the formation conditions of black shales on the basis of analyzing such items as the component of chloroform bitumen "A" and the gas_facies chromatogram of saturated hydrocarbon. Studies show that the Lower Cambrian black shales in Jindingshan of Guizhou Province are sapropelic type and mixed type oil_forming rocks. The black shales are characterized by high content of organic matters, and the organic sources are algae and fungi. Organic geochemical features indicate that black shales were formed in an anoxic sea environment.