The invention discloses a two-dimensional composite hydroxide micron crystal applied to a field effect transistor semiconductor material and a preparation process thereof, and the relation between the conductivity and material layer plate composition, metal ion type, and interlayered anion are discussed. The synthesis of large-size and mono-disperse LDHs micron chips and electrode preparation process can be briefly generalized in following steps: (1) obtaining large-size mono-disperse two-dimensional inorganic nanometer composite hydroxide microcrystals by preparation; and (2) preparing a semiconductor field effect transistor device by employing the electron beam etching and evaporation process. The two-dimensional composite hydroxide micron crystal and the preparation process thereof are advantageous in that by employing an improved reflux method, large-size and mono-disperse two-dimensional LDHs monocrystalline micron chips of different types are synthesized, the micron chips are firstly applied to channel materials of the field effect transistors, the application potential of the materials in the semiconductor electric field is greatly expanded, and certain guidance basis is provided for the application of the two-dimensional materials in the fields of electrochemical catalysis and supercapacitors etc.