Thin film solar cells convert solar energy directly into electricity, provide a renewable, sustainable and clean solution to address the global energy challenges. Organic-inorganic hybrid Perovskite solar cells (i.e., MAPbI3) have demonstrated 22% power conversation efficiency and is developing commercial modules. However, the toxicity of Pb and the instability of organic composition barrier its reliability. Here, we show that lead-free inorganic halide double perovskites as the absorber for thin film solar cells. The inorganic halide double perovskites (i.e., CsSbInCl) with a tunable bandgap in the 1.0-1.8 eV range providing excellent absorbing of the visible spectrum. With a combination of the computational calculation studies, the electronic structures and optical absorption of this group materials are investigated. The solar cell device performance was determined and it is demonstrated that these inorganic halide double perovskites are desired for the next generation photovoltaics devices.