MXene, as a new type of two-dimensional material, has attracted much interest since it was discovered in 2011. However, only few articles discussed the eff ect of MXene fl ake size on its electrochemical performance. Here, a sand milling way is explored to produce nano-size MXene and the MILD method is used to prepare micron-size MXene (1 μm) as a comparison. Meanwhile, a mask-assisted interdigital micro-supercapacitors is prepared to explore the dependence of the electrochemical properties of MXene on their fl ake size. We show that nano-size MXene (200 nm) has a higher ionic conductivity as compared to normal micron-size MXene (1 μm). On the contrary, the larger fl ake size has higher electrical conductivities. As a result, the capacitance of micron-size MXene is better than nano-size MXene (200 nm) because the electrical conductivities are dominant. This research is helpful for further understanding of the infl uence of MXene fl ake size on its electrochemical performance.