devices, including solar cells, photodetectors, light-emitting diodes, and resistive switching (RS) memories. [3-5] However, there are still some obstacles that limiting their industrial applications. [6] The limitation of this family of materials was mainly focused on twofold: first, the organic cations in hybrid organic-inorganic perovskites bring about moisture sensitivity and thermal instability. Second, the lead toxicity constitutes a major concern, hindering its implementation in electronics. [7] Those issues prevent them amenable to a wide variety of device configurations for long term applications. Therefore, the development of alternative lead-free halide perovskites is imperative for the promotion of perovskite-based RS devices. Recently, strategies are devoted to replace lead with nontoxic metal element that has the similar electronic structure. Tin (Sn), is regarded as one of the most feasible replacements for lead, which fulfill the coordination, ionic size, and charge balance prerequisites in perovskite structure. [8-10] More importantly, Sn-based halide perovskites exhibit relatively similar electronic performance, including higher charge carrier mobility and tunable direct bandgap, as compared with Pb-based perovskites. [11,12] In addition, the replacement of organic cation by cesium (Cs) could significantly enhances the thermal stability of the halide perovskites. [13] Mi et al. depict the preparation and properties of CsSnBr 3 , exhibiting higher stability toward heat and moisture than its organic counterparts. [14] Hence, based on the afore-mentioned considerations, it is rationale to investigate CsSnBr 3 as the lead-free all-inorganic perovskite in electronic applications. RS devices, based on inherent switching effects in twoterminal structures, have attracted tremendous attentions due to their excellent advantages, including the high read/ write speed, low programming voltage and high endurance, as compared with traditional flash memories. [15-17] To date, various functional materials, such as traditional metal oxides [18] and perovskite oxides, [19] have been proposed to adopted as the switching media to construct RS devices. In special, recent efforts have been devoted to investigate various halide perovskites as the RS switching layer, including the organicinorganic hybrid perovskite, [20] inorganic halide perovskite, [21] Resistive switching (RS) devices have evolved as one of the most promising candidates in the memory filed due to their excellent endurance and retention, fast switching speed, and extra-high storage density capability. However, the coexistence of toxic lead cations and low RS performance have largely limited the application of halide perovskite in nonvolatile memory filed. Herein, the lead-free all-inorganic perovskite CsSnBr 3 films are synthesized on flexible polyimide (PI) substrates through a one-step chemical vapor deposition (CVD) method to construct environmentally friendly RS devices. The RS devices with Pt/CsSnBr 3 /Pt/PI structure exhibit reliable and reproduc...