Mixing in a chemical industry is a crucial as the quality of a final product depends on the mixing process. Normally, mixing in a microchannel is based on their diffusivity without turbulence flow effect which causes of its laminar flow nature in the microchannel. However, the diffusivity in the microchannel is limited by its short passage. Thus, the objective of this study is to observe the behavior of liquid-liquid mixing (acetone-water) at different condition of feed velocity; 0.01-0.10 m/s, initial concentration by volume fraction; 0.1-0.6 w/w% and design of Y-type microchannel; without and an existence of the obstacle. In this study, the Y-type microchannel is designed by SolidWorks© software and these models then are imported and meshing into AnsysCFX®. This Y-type microchannel has two inlets and one outlet with the distance from the inlets to the Y intersection point is 550 µm and the length of a straight channel is 1200 µm. From this study, it shows a well-mixed flow pattern was observed as the velocity at the inlet A is vA= 0.10 m/s and inlet B is vB= 0.05 m/s, with the average velocity is vo= 0.075 m/s which gives the best mixing condition. Other than that, due to a severe difference on the initial concentration fed at both inlets, create the mixing process requires a longer time or lengthier channel to achieve an equilibrium mixing point due to slow molecular diffusion. Besides, the mixing behavior in the Y-type microchannel with the obstacle shows better mixing’s efficiency performance as the presence of obstacle need an extra interaction and momentum to enhances the liquid-liquid mixing.