In view of the substandard desulfurization index in Yankuang Lunan Chemical Industry Limited Company 240 kt/a methanol production system, the reasons of the substandard desulfurization index and the bad regeneration of desulfurization solution were analyzed. It is pointed out that the desulfurization index exceeds the standard because of the lack of absorption of H2S in the desulfurization regeneration tower, the basic reason of the bad regeneration of the desulfurization solution is that because of crushing and deformation, the part of the broken lower packing of the desulfurization regeneration tower enters into the bottom of the boiling pipe to block the heat exchange pipeline, the external performance of the desulfurization tower is high resistance and pressure difference, and low temperature of regenerator tower. The methanol production system was qualified by optimizing the selection of the regeneration tower and replacement of the packing.