Although lead halide perovskites with tunable band gaps are widely used for photodetection in the visible spectrum, very few studies have been focused on the use of perovskites in ultraviolet detection. Here, we report that MAPbI(3-x)Cl(x)-based photodetectors (PDs) show a response in the ultraviolet spectrum as well as yield very fast photoresponse speed (<80 mu s/90 mu s) and excellent detectivity (10(12) Jones with 365nm lamp) with very low driving voltage (0.3V). The results demonstrate the enhancement of photoelectric performance of the PDs in the ultraviolet spectrum is because the doping of Cl in MAPbI(3) increases the bandgap and the crystalline grain size of MAPbI(3-x)Cl(x) film. Moreover, 10%PbCl2-MAPbI(3-x)Cl(x)-based flexible photodetectors displays remarkable mechanical flexibility.