Drilled cores, thin sections, well logs, image logs and gas testing results were analyzed to systematically study the sedimentary and image characteristics of carbonate platform from the 5th Member of the Ordovician Majiagou Formation in the Ordos basin. The results show that there are two sedimentary facies named “open platform” and “restricted platform” in the research area. The open platform can be classified into interbank sea and intra- plateform subfacies. The restricted platform can be classified into tidal flat and grain bank subfacies. It is possible that grain bank, intra- plateform, dolomitic flat and dolomitic bank microfacies could be favorable reservoir layers. A set of sedimentary facies recognition model image logs, suitable for the platform facies of the 5th Member of the Ordovician Majiagou Formation, was established by comparing the conventional log data with image logs of different depositional microfacies, including block mode, strip mode, layered mode, linear mode, patch mode and dark patch- linear combination mode. This formed the basis for continuous identification and division of the depositional microfacies in a single well. Combined with logging interpretation results and gas test data, the controlling effect of favorable sedimentary microfacies on reservoir effectiveness was further verified. The resulting in- depth understanding of sedimentary facies features and characterisation of favorable reservoirs in the Ordos basin has significance for the exploration of the Lower Paleozoic carbonate reservoirs.