Abstract: [Objective] The dolomite of Ordos basin west margin complex tectonic belt Ordovician Kelimoli Formation as a high quality reservoir for natural gas exploration, its genesis mechanism and the relationship between sedimentary environment and tectonic superimposed transformation, there are still many disputes, which restricts the guidance of oil and gas exploration.[Methods] Based on comprehensive test and analysis including thin-section identification, cathodoluminescence, carbon-oxygen isotope, X-ray diffraction order, geochemical rare earth and trace elements, and strontium isotope, combined with the regional tectonic evolution process, this study explores the genetic mechanism of dolomite.[Results] Cathodoluminescence overall exhibits a relatively weak dark brown coloration with distinct ring bands, and authigenic quartz and saddle-shaped dolomite as hydrothermal minerals are visible, characterized by features of multi-stage recrystallization and burial origin. Carbon and oxygen isotope characteristics indicate that the dolomite has a burial origin. The overall order of the dolomite shows a relatively low degree, and the higher the temperature, the lower the order, suggesting that the dolomite formed in an environment with relatively high temperature and rapid crystallization rate. The rare earth element partitioning pattern is characterized by positive Ce and positive Eu anomalies, indicating that the formation process of dolomite is the result of internal fluid adjustment and redistribution within the diagenetic system under relatively closed, high-temperature, and high-pressure conditions. The lower the Sr content and the higher the Fe and Mn element contents, overall showing the characteristics of multi-stage superimposed modification under deep burial conditions. The strontium isotope values of medium to coarse-grained dolomite are significantly close to the average value of crustal source strontium isotopes, which may have been affected by crustal source strontium carried by synchronous tectonic activities.[Conclusion] Research indicates that dolomite formation is primarily attributed to deep burial, while also undergoing superimposed tectonic fluid modification. The evolution of Ordovician Krimolli Formation dolomite is closely linked to the deep fault system. During the co-deposition period, this fault system controlled the development of high-energy terraces. In the subsequent tectonic activity phase, the deep fault system became a fluid migration channel, facilitating the superimposed modification of dolomite bodies.[Significance] Research results can provide a fundamental support for the efficient exploration of oil and gas resources.