A method for preparing CuAlO2 thin film by 
microwave hydrothermal method. First, 
copper acetate monohydrate is added to 
ethylene glycol to obtain solution A; then 
aluminum nitrate nonahydrate is added to solution A and the pH value is adjusted to 2.0-4.0 to form a uniform precursor  material solution B; pour the B solution into the hydrothermal reactor, and immerse the 
silicon substrate in the B solution; seal the hydrothermal reactor, and put it into the MDS-8 type temperature-pressure dual-controlled 
microwave hydrothermal reactor;  Select 
temperature control mode or 
pressure control mode for reaction and then naturally cool to 
room temperature; open the hydrothermal reactor, take out the 
silicon base, then wash several times with deionized water, absolute 
ethanol or isopropanol, and dry to obtain CuAlO2 film  .  The invention adopts 
microwave hydrothermal method to prepare CuAlO2 thin film.  Not only the preparation cost is low, the operation is simple, and the reaction period is short, but also the product has high purity, complete grain development, uniform 
particle size distribution, controllable shape and no 
calcination treatment.  The CuAlO2 thin film prepared according to the preparation method of the present invention is uniform and dense, and has strong bonding force.