Gas sweetening is one of the important purification processes which is employed to remove acidic contaminants from natural gases prior to meet transport requirements and sale gas specifications. The natural gas processing plant Missan Oil Company / Missan Oil Fields Operation Division / Buzurgan Oil Field of Natural Gas Processing Plant , specifically the Sulfur Removal Unit(SRU), is one of the first manufactory established to treat the associated natural gas coming from the Buzurgan Oil Fields containing high levels of acid gases to carry out the process of sweetening it and exporting to its consumption resources, as the electric power plants are among the most beneficiaries of consumers from Processed gas and crude oil processing plants, followed by the Missan oil refinery, which is used in the refining of crude oil. The purpose of this study is to evaluate the performance and efficiency of the gas treatment plant by using an Aspen Hysys simulation program V10 to accomplish a steady-state simulation with use a single MDEA solvent(45 wt%), MDEA-MEA solvents blend(40-15 wt%) and Sulfolane-MDEA solvents blend(40-20 wt%), and investigate the some of important parameters in the sweetening process through study the effect of operational parameter change (feed gas temperature ,feed gas flow rate ,solvent concentration) , and compare their results with each other. The sulfur removal unit was investigated by simulating each of the mentioned solvents.