In this present study, the mixing of two incompressible miscible fluids with different density and viscosity has been investigated in a two-dimensional microchannel equipped with an oscillating stirrer in different excitation frequency. Although most studies in the field of fluid mixing, have been studied the mixer performance when the two fluids were absolutely identical, but the mixing make sense when two fluids has been non-uniformity such as different temperature, concentration or properties. The aim of this study is to evaluating the effect of various properties of the fluids in mixer performance and mixing value. Simulation has been performed in Re=100 and Sc=10, between 0.1 to 1 strouhal number by using element based finite volume method by means of commercial code CFX. Mixer performance has been evaluated in three different modes: mixing of two identical fluids, mixing of two fluids with different density and mixing of two fluids with different viscosity. The results show that, mixing of the fluids with different properties leads to change in mixer performance, and has unique performance in each case. In comparison with similar properties fluids, mixing of fluids with different viscosity and density show lesser inclined in mixing. It has been shown that variation of strouhal number has lesser effect on mixing index changes. The ratio of maximum mixing index changes to base mixing index in the case of different density and viscosity is 54.01 and 51.15 percent, respectively, while the value is 577.94 percent for the mixing of similar fluids.