In order to clarify the influence of humidity on the properties of Zr-doped In2O3 (IZrO) during manufacture of heterojunction solar cell, water vapor was intentionally introduced into the process chamber of a conventional DC magnetron sputtering production line. The result shows a close dependence of the optical and electrical properties on the doping of hydrogen, incorporated by water vapor introduction, which participates into the formation of carrier scattering centers such as ionized impurities and oxygen vacancies. To improve the optical performance of IZrO thin film for silicon heterojunction solar cell, a new structure with an ultrathin layer of Sn-doped In2O3 was developed on the IZrO thin film. With the optimum processing condition, the short-circuit current was largely gained and the heterojunction solar cell succeeds in J(SC) 38.72 mA/cm(2), FF 82.39% and the efficiency up to 23.59%.