In recent years, a new family of two-dimensional (2D) transition metal carbides and/or carbonitrides labeled MXene, have greatly attracted the attention of researchers. Due to unusual hydrophilicity, electrical conductivity, flexibility, and pseudo capacitance, MXenes have great potential application in energy storage, water desalination, catalysis, electromagnetic interference shielding, transparent conductive films and so on. However, MXene perform poor stability because of the structural defects, active transition metals and termination groups. These greatly destroy the sheet structure and decrease their conductivity and therefore restrain their application fields. In this review, the structure and synthesis methods of MXene are briefly introduced. Then we focus on current researches of the stability of MXene. The mechanism of oxidation is also discussed. Ti vacancies and the edge of MXene sheets have been identified as the preferential sites for oxidation in MXene sheets. Based on this, the methods of improving the stability of MXene including controlling storage environment, improving the synthesis method, annealing in atmosphere, and modification based on surface electric state are further discussed. Firstly, the requirements to store MXenes should be low temperature, desication and oxygen isolation. Secondly, soft etching method should be applied to synthesize MXenes for reducing of the defect density of the MXene sheet surface. Then, annealing of MXenes in atmosphere can tune the surface structure and functional groups for improving the stability of MXenes. Lastly, more methods have been applied to improve the stability of MXenes based on their surface electric state. Since the surface of MXene sheets is electronegative, the oxidation of MXene can be slowed down by loading cations into the MXene sheets. Similarly, since the edge of MXene sheets is electropositive, polyanions can be absorded onto the edge to protect MXene sheets. Finally, compositing metal oxides, organic macromolecules and nano carbon on the surface can also improve the stability of MXenes. Our idea of improving the stability of MXenes is also briefly introduced.