In order to evaluate the corrosion behavior in oil and gas field condition it is important to simulate the corrosion condition at the laboratory test. Regarding the parameters for indicating the severity of corrosion partial pressure of hydrogen sulfide and carbon dioxide temperature concentration of chloride ion and pH of the solution should be taken into consideration. In these parameters pH of the solution relatively seems to fluctuate during the test. From these points above the test method for simulating pH by using buffer system is significantly adopted.In this research estimation of buffer capacity for some buffering system was conducted. Buffer capacities which are resistances of pH change in the solution were measured in laboratory and calculated by chemical thermodynamics. In addition to the results corrosion tests of CRA such as S13Cr were carried out to determine the corrosiveness in the variety of buffering systems. The validation of buffering system which can simulate an actual oil and gas condition will be discussed.