The invention discloses a method for preparing a CdSexTey quantum dot optoelectronic film. The method comprises the steps that (1) 0.4317-1.2953 g of Cd(NO3)2 4H2O is weighed and placed to a beaker, 0.2689-0.8069 g of citric acid serves as a complex agent and is added to the beaker, water is added, and a complex aqueous solution of 10 mL A is prepared; (2) 0.0399-0.1197 g of TeO2 is weighed and placed in the beaker, a 1mol/L NaOH solution is dropped in the beaker until the TeO2 is dissolved completely, 0.0432-0.1297 g of Na2SeO3 and water are further added, and a solution B of 10 mL is prepared; (3) the complex aqueous solution A and the solution B are mixed, so that a solution C is obtained; (4) the solution C is placed in a water bath at 45 DEG C to 55 DEG C and electro-deposition is conducted on the solution for 20 minutes to 40 minutes at the direct voltage of 2.5 V to 3.5 V and under the condition of magnetic stirring, wherein ITO conductive glass serves as a cathode and a platinum sheet is an anode. The method has the remarkable advantages that the CdSexTey quantum dot optoelectronic film is obtained through an electrochemistry codeposition method, the preparing technology is convenient, efficient, free of pollution and low in cost, and the prepared CdSexTey quantum dot optoelectronic film is high in photovoltage value.