The invention discloses a cadmium telluride film solar cell and a preparation method thereof. A structure of the cadmium telluride film solar cell is that the cell comprises a substrate with a conducting layer, and the substrate is sequentially deposited with a cadmium sulfide layer, a cadmium telluride layer, a tellurium-rich layer, a back contact layer and a back electrode. According to the method, a treated low-toxicity compound cadmium is adopted as a cadmium source, and treated tellurium or telluride is adopted as a tellurium source to prepare the cadmium telluride film solar cell; the cadmium source and the tellurium source undergo a chemical reaction in a certain molar ratio to prepare cadmium telluride particles with uniform particle size; and then the cadmium telluride particles are purified, cadmium telluride and a low boiling-point solvent containing polyvinylidene fluoride are mixed to obtain sol, and a cadmium telluride film is prepared by a coating method. The method prevents human bodies from contacting high-toxicity cadmium element and cadmium steam, and also avoids environmental pollution at the same time.