In this paper, the critical and reduced properties of several real fluids such as Ne, N2, CO, and etc., are studied. For this goal, the Sutherland potential model and the perturbed virial expansion are applied. We also use three different compressibility factors ( k T P B ï² ) and show their influence to calculate the reduced and critical temperatures and densities of the fluids. According to the obtained results, it is deduced that the critical and reduced properties for some fluids (no all) are in good agreement with experimental data. This means that the Sutherland potential model can not be used to determine the critical and reduced properties of any real fluids. We also found that the best results can be obtained when the Sutherland potential model has been applied with the second compressibility factor.