The Xiamaling Formation study has progressed much since it was firstly named as Xiamaling Shale in Western Hills, Beijing, in 1920. The Formation is reviewed here from different perspectives after nearly one hundred years, including its lithology, stratigraphic succesion, sedimentary environment, regional differences, chronostratigraphy, palaeontology, oil/gas possibility, diabase sills in it, its significance for paleoceanic evolution, basin type and also evolution. Thus we could have a more comprehensive, detailed and profound understanding of the formation and its significance for the evolution of both North China and the Earth in the Proterozoic. The Zhaojiashan section, together with the suggested Xiahuayuan standard section, are described carefully for its lithological variation and sedimentary environment evolution. The boundary of each member are also further modified and defined. Contrasting of the 4 important sections, toghther with the other 10 sections and the marginal deposition in the North China Craton, outline the remaining basin and their vertical similarities and also differences for the formation. The 4 memmbers of the formation are comparable, although the upper part may be eroded after deposition and the thickness of the succesion can be variable because of possible lateral facies change. The biotic found and its chronological study advancement are also summarized. The study focuses concerning the formation are reviewed, including: (1) their organic content and corresponding hydrocarbon generating potential, (2) evidence for the ocean redox structure in the Mesoproterozoic, (3) the extensive basic sills and their tectonic significance, and (4) indication for the basin type and evolution of the so called Yanliao aulacogen. We conclude the formation should be further studied for its basic geological aspects firstly. Its high resolution stratigraphic correlation, chronostratigraphic framework improvement, origin of the rhythm and provenance analyses can also be done in the future. Other stratigraphic segments and later deformational—tectonic events in the Norch China, the corresponding Mesoproterozoic geologic recoreds in the word should also be concerned for a fully understanding of the formation.