In order to study the semi-transparent thin film solar cell with better material stability, use direct current magnetron sputtering technique to deposit cuprous oxide(Cu₂O) thin film and zinc oxide(ZnO) thin film, forming the Cu₂O/ZnO heterojunction. By using scanning electron microscope, X-ray diffractometer, raman spectrometer, thin film measurement instrument and solar simulator, the influence caused by Cu₂O layer prepared under different Ar/O₂ gas flow ratio on material properties, optical properties and photoelectric properties of heterojunction is studied. Results show that the Cu₂O/ZnO heterojunctions produced under the certain Ar/O₂ gas flow ratios have certain photoelectric conversion ability under the standard simulated sunlight of AM1.5, which can be used as the energy conversion unit of the semi-transparent solar cell.