Parallel to the booming of all‐inorganic CsPbX3 halide perovskites, the growth of lead‐free perovskites is accelerating, with the efficiency values of over 10% being realized. Eco‐friendly and stable halide double perovskites with superior stability are considered as an encouraging alternative to address the stability concerns related to the lead halide perovskites. Recently, Cs2SnI6 with defect perovskite structure has appeared as a “superstar” material owing to its environmental friendliness and exceptional stability. Herein, an iodine‐rich strategy (IRS) is developed based on the modified two‐step method for the fabrication of lead‐free Cs2SnI6 films. In addition, the impact of the reaction temperature on the properties of the resultant films is systematically investigated. The results reveal the improvement in the crystallinity and phase stability of the films, suggesting that the proposed IRS successfully inhibits the decomposition of Cs2SnI6 films. The optical measurements confirm the n‐type nature of Cs2SnI6 with bandgap varying from 1.23 to 1.38 eV. The photoluminescence of the films increases gradually with the addition of I2, presumably owing to the reduction of nonrecombination sites. The current work provides valuable direction for the fabrication of Cs2SnI6 devices for green energy applications.