NOVELTY - A copper-indium sulfur array film preparation method involves dissolving indium salt, copper salt, and dispersant in first solvent, and stirring, to form solution. Sodium borohydride is added in a second solvent. The solution is separated and washed by centrifugation to obtain copper indium alloy nano particle. The nanoparticle is dispersed in an organic solvent to prepare copper-indium alloy ink coat followed by directly transferring onto the substrate. The obtained copper-indium precursor film is sintered in hydrogen sulfide/argon atmosphere, to obtain finished product.    USE - Method for preparing a copper-indium sulfur array film for use in a solar battery absorption layer.    ADVANTAGE - The method enables preparing copper-indium sulfur array film by adopting simple device with better trapping effect, reduced reflection, high absorption of light in a simple and cost-effective manner.    DETAILED DESCRIPTION - A copper-indium sulfur array film preparation method involves dissolving indium salt (0.01-0.12 mol/l), copper salt (0.01-0.1 mol /l), and dispersant in a first solvent, and stirring at 120-180 degrees C until it is completely dissolved, to form solution. Sodium borohydride is added in a second solvent, and the mixture is reacted at 120-180 degrees C for 10-30 minutes. The solution is separated and washed by centrifugation to obtain copper indium alloy nano particle. The copper alloy nanoparticle is dispersed in the organic solvent to prepare copper-indium alloy ink coat followed by directly transferring the copper-indium alloy coated onto the substrate to form copper-indium precursor film. The precursor film is sintered in hydrogen sulfide /argon atmosphere, at 450-600 degrees C for 10-60 minutes, and the temperature is increased to 1-10 degrees C/second, at pressure of 5-30 Torr, to obtain copper-indium sulfur array film, where the indium salt is indium, the copper salt is copper chloride or copper sulfate, and the dispersant is polyvinyl pyrrolidone, first solvent and second solvent are diglycol, or glycol, and the mole ratio of the indium, and copper salt is 1.03-1.15:1, and the organic solvent is ethanol, polyvinylpyrrolidone/ethanol, or ethylene glycol/glycol/ethanol solution.