In this study, computer modeling and comparative works have been performed to obtain highly pure dimethyl sulfoxide (DMSO) which is used for fiber spinning solvent for two different distillation sequences. These two distillation sequences remove methanol and water and recover DMSO solvent from the mixture of methanol and water using two distillation columns. Non random two liquid mixture (NRTL) liquid activity coefficient model was used for the modeling of each binary vapor-liquid equilibria for DMSO, methanol and water systems and we used PRO/II with PROVISION release 7.1 as a commercial chemical process simulator. As a result of computational simulation, we obtained a highly pure DMSO with its purity over 99.9 wt% and water contents which is main impurity was very low weight percent under 500 ppm.