The halide-mixed CH3NH3PbX3-yIy (X = Cl, Br) (MAPbX3-yIy) films have tunable band gaps for applications in perovskite solar cells (PSCs). The performances of PSCs can be further adjusted by halide mixing of perovskite films. Preparing the MAPbX3-yIy films by low pressure vapor-assisted solution process (LP-VASP) could achieve pin-hole free perovskite films, which has the potential to mass production of perovskite films. In this study, the MAPbX3-yIy (X = Cl, Br) thin films are prepared by exposing PbI2 films in various amine salts vapor and applied to fabricate the planar PSCs. Systematical structural-property investigations on the MAPbI3-yXy (X = Cl, Br) thin films demonstrate that the halide-mixed perovskite films could be achieved by adopting different amine salts. The MAPbI3/MAPbCl3 biphasic constitution is observed in perovskite films using pure MACl, while the MAPbI3-yCly (y ≈ 0) could be obtained using MACl:MAI mixture. Using pure MABr or MABr:MAI mixture, the MAPbBr3-yIy films are prepared. The XRD and XPS results indicate that there is no remnant Cl in the MAPbI3-yCly (y ≈ 0) films, nor I in the MAPbBr3-yIy (y ≈ 0) films. Because the amine salts are excess, the halogen in amine salts mainly decide the halogen in CH3NH3PbX3 in our study. Moreover, the MAPbCl3-yIy (y ≈ 0) and MAPbBr3-yIy based PSCs are demonstrated to behave better stability than the MAPbI3 based PSC under continuous illumination at AM 1.5G. Furthermore, the planar PSCs based on 15 wt% MACl mixed MAI exhibit power conversion efficiency of 17.3% with good stability over 3600 h.