The mixed halide CH3NH3PbI3-xClx crystalline thin film has been prepared by two-step solution-processed repeated dip coating method at an ambient atmosphere. X-ray diffraction study reveals the presence of tetragonal and cubic phases in deposited film. Raman study confirms the metal halide bond in the inorganic framework and organic CH3 stretching/bending of C-H bond in CH3NH3PbI3-xClx perovskite. Scanning electron microscopy shows that cuboid and polyhedral-like crystal grains of 100nm to 2m may find applications in optoelectronics. The perovskite CH3NH3PbI3-xClx thin film shows high spectral absorption coefficient of the order of 10(6)m(-1). In optical band gap study, we found the coexistence of cubic and tetragonal perovskite phases. The energy band gap is dominated by cubic phase having E-g=2.50eV over tetragonal phase with band gap E-g=1.67eV. The room-temperature photoluminescence study confirms band edge, shallow and deep-level emissions. The temperature-dependent cathodoluminescence study shows red, green and ultraviolet emissions. The dominating green luminescence evolved for cubic phase at 2.51eV. The red and ultraviolet emissions are also found for mixed-phase CH3NH3PbI3-xClx thin film, suitable for preparation of light-emitting devices.