Fluid flow in the microchannel is limited to the low Reynolds number regime. As a result

mixing of solutions with different concentrations in the microchannel is inherently diffusion dominated，requiring a long mixing channel and retention time to attain a homogeneous solution. In this paper the flow characteristics in the two-dimension closed-end microchannel electroosmotic flow were simulated，and the mixing efficiencies of the closed-end microchannel electroosmotic flow applying different electric field intensities were compared. The results showed that because of existing non-uniform induced back pressure，there were two annular flows in the whole closed-end microchannel，enhancing the convection effect and leading to a shorter mixing time and higher mixing efficiency.