All inorganic CsPbI3-xBrx perovskites have been widely used in photodetectors due to their excellent optoelectronic properties and simple preparation processes. Here, high-performance flexible photodetectors based on inorganic CsPbI3-xBrx perovskites are demonstrated, which are achieved by a modified solution-processed method. When biased at a low voltage of 10 mV, the device yielded fast response speeds (90 μs /110 μs for CsPbI2Br PDs and 100 μs/140 μs for CsPbIBr2 PDs), a high on/off ratio of 104, and a high detectivity about 1012 Jones. Meanwhile, the devices showed outstanding environmental stability and mechanical flexibility. The periodic I-t curves had negligible fluctuation (< 5%) after storing in air atmosphere for 30 days or bending for 100 times. The results indicate that CsPbI3-xBrx perovskites have great potential in photodetection areas and pave the way to achieve high-performance flexible PDs.