For the issue of tail gas with high SO₂ treatment in natural gas processing plant, a dual-alkali desulfurization process is discovered in this paper with the establishment of experimental device to verify and optimize the process. Upon continuous and stable operation, test for multi-working conditions and large amount of experimental data analysis, the new dual-alkali desulfurization process was proved to be high efficient, small in floor area, easy to operate and maintain, free of waste liquid and residual, which is of reference significance for solving the problem of tail gas with high SO₂ treatment in natural gas processing plant.