Based on a detailed microobservation by scanning electron microscope (SEM), we proposed a possible new discovery of bacterial fossil in the siliceous shale of the Songlin early Cambrian black rock series, Guizhou Province, South China. The fossils are characterized by a width of 200-250 nm with uneven surfaces and high abundance of total organic carbon (TOC). By a comparison with the organism with similar morphology that has been reported previously, it is concluded that the fossils discovered here have representative size and structure of bacteria. Thus, we suggested that the fossils may be protogenetic microbioids with typical bacterial structure. These fossils are present in multiple locations, such as the surface of quartz grains, inter-grains and even within the grains. Hence, it can be implied that the bacteria may play important roles in the precipitation of quartz. These results provide new microscopic information on the understanding of the formation of siliceous rocks.