Abstract: Heshui area of Ordos basin is an important exploration area in recent years, and the study of reservoir heterogeneity can provide more scientific basis for production. In order to make clear the heterogeneity of Yanchang 2_3 reservoir in Heshui area, based on the fine division and correlation of small layers, the heterogeneity characteristics of chang2_3 reservoir are studied by using drilling core, well logging, analysis and testing data, through three aspects of heterogeneity in layers, between layers and on the plane. The results show that the heterogeneity of Chang 2_3 reservoir is closely related to the sedimentary facies zone. The study area belongs to delta front sub facies deposition, and the porosity and permeability of microfacies such as distributary bay and underwater natural levee are relatively low, while the porosity and permeability of underwater distributary channel microfacies and the favorable sedimentary facies zone with larger thickness of sand bodies are gradually increasing, that is to say, the high porosity zone is right the high permeability zone, and the sedimentary facies zone plays an important role in controlling the reservoir heterogeneity.