Shale water absorption caused by hydraulic fracturing changes the reservoir structure and mineral composition. It is of great significance to conduct shale water absorption research to guide shale gas development. Dynamically monitor the process of shale water absorption, analyze the influence of shale water absorption on reservoir structure and mineral composition, and form relevant qualitative and quantitative analysis methods. The research results show that: 1) Under the action of the strong water absorption capacity of clay minerals and other components, water quickly enters the interior of the shale through the primary fracture, and then a slow imbibition process occurs, the progress of mineral dissolution and hydration results in new secondary fractures of shale near the primary fracture. 2) Clay mineral rapidly hydrated in the initial stage of shale water absorption. Hydration mainly occurred in mineral components rich in Na⁺ and SO₄^2- . Analysis indicated that illite was the main component of clay minerals hydrated. 3) The dissolution strength of brittle minerals such as iron dolomite is significantly higher than the hydration strength of clay minerals. The analysis shows that the dissolution of brittle minerals and clay hydration together lead to changes in mineral composition before and after shale water absorption. By qualitatively and quantitatively analyzing the changes in the reservoir structure and mineral composition during shale water absorption, the influence law of shale water absorption on the shale structure and composition was preliminarily obtained in order to guide the actual production and development.