Herein, a simple method was developed for the first time to pretreat sulfonic acid resin-based catalysts using different solvents (such as n-hexane, toluene, acetone, methanol, dimethyl sulfoxide, and sulfolane), and the as-treated resins were applied in DMM carbonylation. Except for sulfolane, the treatment solvents with a higher dipole moment resulted in a higher turnover number (TON) but lower DMM conversion and MMAc selectivity. SA_resin-sulfolane-393 K exhibited excellent activity and stability for 50 h with an STY of 3.15 mmol_MMAc (gcat h)⁻¹ and nearly 100% MMAc selectivity. The Arrhenius plot of SA_resin-sulfolane-393 K was generated from the reaction rate data at various temperatures, and the apparent activation energy was calculated to be 18.39 kJ mol⁻¹. Karl Fischer analysis, in situ FT-IR analysis of CO adsorption, and static CO adsorption method indicated that the residual H₂O in SA_resin was significantly reduced and the CO adsorption capacity was obviously enhanced. The nitrogen adsorption–desorption isotherms, FT-IR spectra, and SEM and EDX-mapping images of SA_resin-sulfolane-393 K proved that a larger average pore diameter and pore volume were generated, and sulfolane indeed entered the resin and changed the chemical composition of SA_resin. The FT-IR spectra of the pyridine pre-adsorbed samples and Hammett acidity function (H₀) confirmed that SA_resin-sulfolane-393 K exhibited a stronger acid strength. The unusual activity and stability of SA_resin-sulfolane-393 K are attributed to its stronger acid strength, low H₂O content and excellent CO adsorption capability.