Objective To discuss the high-frequency sequence division and its control on reservoirs in carbonate strata. Methods This study used the Th/U curve in natural gamma ray spectrum logging as the indicator curve. combined with the Fischer diagram and lithological assemblage sequence， high frequency sequence of Ma{}_{\mathrm{5}}^{\mathrm{1}\mathrm{⁃}\mathrm{5}} sub-member of Majiagou Formation was divided quantitatively in the Tao 7 block of the Ordos Basin. Results The research shows that the Th/U value in natural gamma-ray spectroscopy logging can be used as an indirect alternative index of astronomical orbit in carbonate strata. The high-frequency sequence can be effectively divided by quantitative and qualitative analysis methods such as spectrum analysis combined with the Fischer diagram and lithologic lithofacies analysis. The Ma{}_{\mathrm{5}}^{\mathrm{1}\mathrm{⁃}\mathrm{5}} sub-member in the Tao 7 block can be divided into one third-order sequence， six fourth-order sequences， and twenty fifth-order sequences. It is estimated that the average deposition rate of the Ma{}_{\mathrm{5}}^{\mathrm{1}\mathrm{⁃}\mathrm{5}} sub-member is 5.03 cm/kyr， and the deposition time is approximately 2.43 Ma. The gypsum pseudocrystal dolomite， which developed in the upper part of the intertidal zone and in the top of the high-frequency sedimentary cycle with upward shallowing， is the dominant facies belt for reservoir development. Near the high-frequency sequence boundary of the fourth-order sequence is the favorable interval for reservoir development. The early karst caused by frequent changes of sea level was the main driving force for the formation of model pores in the Ma{}_{\mathrm{5}}^{\mathrm{1}\mathrm{⁃}\mathrm{4}} sub-member and laid the foundation for the krast in later supergene stage. Conclusions Quantitative identification and division of high-frequency sequence is important for reservoir prediction in carbonate strata.