According to the observation of cores and thin slices from 63 wells and the analysis of a great many data from cathode luminescence, carbon and oxygen isotope, inclusion enclave test and energy spectrum analysis, Cambrian-Lower Ordovician dolostones are characteristic of four genesis corresponding with four kinds of dolostone including sabakha dolostone, seepage refluxion dolostone, buried dolostone and hydrothermal dolostone. The former two are controlled by sedimentary facies, and the latter two are dominated by lithofacies. Sabkha dolostone developed in intertidal -supratidal flats under synsedimentary-penesynsedimentary evaporate diagenetic environments while seepage refluxion dolostone formed in lagoon. Buried dolostone developed in deep or shallow burial environments during burial stage while hydrothermal dolostone formed in deep burial environments. Petrologic and geochemical features of these four kinds of dolostone are generalized. It is cognized that the dolomization mechanism of ancient marine formations in the superimposed basin is complicated and dolostones are characterized by varied types. Texture of dolostones is not only closely related with sedimentary facies but also is reformatted by multiple dolomizations during buried stage.