The invention relates to a preparation method of CuInSe2 with a chalcopyrite structure and CuIn1-xGazSe2 nano particles. Firstly, a metal precursor solution containing Cu+ or Cu2+, In3 or Ga3+ cation and a Se powder precursor solution are respectively prepared, and then the metal precursor solution and the Se powder precursor solution are mixed and uniformly stirred, and the solution is heated to 200-285 DEG C. with high purity nitrogen protection and reacted for 0.5-2 hours, and then the CuInSe2 or CuIn1-xGazSe2 nano particle solution is obtained, after high speed centrifugation, cleaning and drying steps, the CuInSe2 or CuIn1-xGazSe2 nano particles are obtained. The CuInSe2 or CuIn1-xGazSe2 nano particle has the advantages of chalcopyrite crystal structure, good dispersibility and high phase purity, and the element ingredient approaches to the stoichiometric ratio, thereby laying a foundation for preparing a high conversion efficiency film solar energy battery. The invention employs cheap metal salt and selenium powder as precursors, and employs a simple one-pot synthetic method, and has the advantages of simple operation, short synthesis period, strong repeatability without injection, and is suitable for mass production.