Abstract: Exceeding the limit of underground hydrogen sulfide not only harms operators, but also damages underground equipment.The concentration of hydrogen sulfide in water in a coal mine roadway in Shanxi is 228.19 mg/m³, and 45.64 mg/m³in the air, rendering it a high hydrogen sulfide coal mine.The method of coal seam drilling and alkali injection is used to control hydrogen sulfide.In order to determine the optimal parameters of alkali injection, this paper uses COMSOL Multiphysics software to carry out single-hole and double-hole alkali injection numerical simulations on the process and effect of coal seam alkali injection to treat hydrogen sulfide.The simulation results of single-hole and double-hole alkali injection show that: the farther away from the drilling center, the lower the alkali injection pressure on the coal seam.The longer the alkali injection time, the larger the diffusion range of the alkali solution.And the diffusion speed of the alkali solution gradually decreases as the diffusion range becomes larger.When the distance of double-hole alkali injection is too close, the cross-flow will cause the diffusion range of the alkali solution to become smaller at the same time.The optimal simulation scheme is as follows: the hole distance is 10 m, the pressure is 8 MPa, and the alkali injection time is 48 h.After alkali injection at the 13103 working face, a 28 d on-site data monitoring was carried out.The maximum hydrogen sulfide concentration in the return air flow was 9.13 mg/m³, which did not exceed the limit during the mining, indicating that the optimal alkali injection parameters can guide the coal seam alkali injection work.