BiOI/BiOBr heterojunction composite catalytic material was synthesized by solvothermal method, its degradation ability of rhodamine B was investigated, the photocatalytic performance of the BiOI/BiOBr heterojunction, BiOBr and BiOI was compared. The structure, morphology and optical properties of the samples were characterized by X- ray diffraction(XRD), field emission scanning electron microscopy (FESEM), UV-vis diffuse reflection spectrum (UV-vis DRS), steady-state and transient-state PL spectra. The degradation rate of rhodamine B was analysised by spectrophotometry, the results show that the BiOI/BiOBr heterojunction photocatalytic materials have good degradation ability to 100 mg/L rhodamine B, it showed that the degradation rate of rhodamine B was 100% in forty minutes, which was also significantly higher than the degradation rate of pure BiOBr (80%) and BiOI (72%). The first order kinetic rate constant is was 0.1028 min-1, which are 2.6 and 3 times of BiOBr(0.0403 min-1) and BiOI(0.0344 min-1) respectively. This heterojunction photocatalyst can not only effectively promote the photogenerated charge separation but also maintain the strong redox ability of the composites, which may be the internal reason for the efficient degradation of Rhodamine B by BiOI/BiOBr heterostructures.