Abstract: In order to improve the stimulation effect of acid fracturing, the diverting acid of water soluble inorganic salt particle was prepared according to the coionic effect and its preparation process and formula optimization were studied in this paper. It is shown that the solid content, one of the important factors influencing plugging and diverting effect can be controlled by adjusting acid and salt proportions and the diameter of water soluble inorganic salt particle can be controlled between 10.0 μm and 40.0 μm by changing the stirring rate, the dropping rate of NaCl solution and the type and adding order of dispersing agent. Double-core flow experiment was carried out to test the properties of the diverting acid of water soluble inorganic salt particle in the laboratory. Its breakthrough time is 15 min, breakthrough pressure is 2.8 MPa and the transformation rate of low-permeability core after acidizing is 45.5%, indicating good diverting property of this diverting acid. During the field application, both tubing pressure and casing pressure rise after the injection of diverting and acidizing fluid, indicating the success of temporary plugging and diverting. After acid fracturing, the flowback rate is up to 77.5% and the gas production rate is 13.6×104 m3/d, verifying the feasibility of water soluble inorganic salt particle to act as diverting material.