In the 1960s, Pettijohn and Potter classified the geologic processes which formed primary structures into erosion, transportation, deposition, and deformation. The primary sedimentary structures are defined as those structures formed by the above processes during sedimentation or after sedimentation while before consolidation. They include various types of bedding, marks on the bedding surface, and deformational phenomena. In their classification on the primary sedimentary structures, stromatolites are defined as positive growth structures projecting from the former depositional surfaces, and are formed by the combined action of microbes and synsedimentary cementation. From the middle 1990s  to the present day, sedimentologists realized that microbes can also form a kind of primary sedimentary structures which do not project from the sedimentary surface, and they are formed by the combined action of microbial mat（or film）and all kinds of physical actions such as erosion, transportation, deposition and deformationThis kind of sedimentary structures are defined as the primary sedimentary structures formed by microbes, which belong to the fifth kind of primary sedimentary structures. Stromatolites were mainly developed in the Precambrian and the Phanerozoic shallow water environments which were not strongly changed by metazoan. Similar to that, the sedimentary structures formed by microbes were also mainly developed in the Precambrian and the tidal flat and lagoon environments in the Phanerozoic which were not strongly changed by metazoan. Therefore, the studies of this kind of sedimentary structures（the fifth kind of primary sedimentary structures） have great significance in the reconstruction of the Precambrian environments. The observation and preliminary study of the primary sedimentary structures formed by microbes in the Mesoproterozoic in Yanshan area provide a useful basis for the further study in the future. These structures include the palimpsest ripple, the wrinkle structure, the microbial sand chip and the spindle crack developed in the Chuanlinggou and Dahongyu formations. They represent the primary sedimentary structures formed by microbes in clastic rocks. The largescale palimpsest ripple and wrinkle structure developed in the nonstromatolitic limestones of the Member 3 of the Gaoyuzhuang Formation represent the primary sedimentary structures formed by microbes in carbonate rocks of the Mesoproterozoic.