The Taiyuan Formation limestone reservoir is a carbonate reservoir mainly composed of calcite and dolomite, characterized by strong heterogeneity, inaccurate pore fracture description, high Young's modulus, and small reservoir stress difference. During the reservoir transformation process, problems such as large liquid filtration loss, difficult fracture formation, and lower than expected recovery rate often occur. To solve the above problems, by studying the acidification transformation process and parameters, conducting mechanical parameter testing under acid pressure conditions, studying the crack propagation law under acid pressure and sand composite and multi lithology combination, and conducting research on acid etched crack and sand support diversion, the mechanism of composite transformation production increase was clarified, and the formation transformation plan was optimized. The results indicate that, based on the cumulative production over five years, an increase in HCl acid content enhances the fracture conductivity; Production increases with the increase of sand volume; The maximum yield is achieved when the proppant ratio between 1: 2 and 2: 1 is between 40 ~ 70 mesh and 70 ~140 mesh; As the viscosity of the slippery water increases, the crack conductivity gradually increases, and the maximum production value is achieved between 15 ~ 25 mPa·s. Taking the TE well as an example, the optimal parameters for the transformation are pump injection parameters of single-phase acid 100 m³, ceramic particle (35 + 1.1) m³, sand ratio 12.5%, displacement 3.0 ~ 6.0 m³/min, pre fluid 280 m³, carrying sand fluid 280 m³, and pre fluid ratio 50.0%. After composite transformation, the fracture diversion capacity is significantly improved, laying the foundation for the economic and efficient development of limestone reservoirs and improving recovery rates.