A new class of semiconducting materials called organic-inorganic halide perovskites hereafter could lead to commercial photoelectric devices due to the ultrahigh-performance and low cost. Meanwhile, perovskite-based photodetectors also have a rapid evolution in recent years. On the part of optical sensors, visible light detection is crucial for many applications, including imaging, medical treatment, industrial auto-control and so on. However, it is difficult for traditional preparation techniques to reach large-scale preparation accompanied by splendid performance of the device. Herein, we reported a method for high performance photodetctor by brush-coating. The device structure of the photodetector is ITO/PEDOT:PSS/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>2.4</sub>Br<sub>0.6</sub>/PC<sub>61</sub>BM/C<sub>60</sub>/LiF/Ag, and the composite perovskites are consisting of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> and CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> with optimized mixing ratio which is crucial for not only enhancing the photon absorption but also ensuring a adjustable detection range .The device shows an excellent detectivity of ~10<sup>11</sup> Jones under the illumination of 650 nm light at the bias of -0.5V. Due to the brush-coating process, the dark current is effectively suppressed down to 10<sup>-10</sup> A. The present results suggest a promising strategy for fabricating outstanding perovskite-based photodetectors and provide a potential strategy for large-area fabrication.