Abstract: A series of Ag₃PO₄/BiPO₄ composite photocatalysts with different doping proportion of BiPO₄ and Ag₃PO₄ were synthesized by a hydrothermalmethod at different pH. The photocatalytic activity was investigated for degradation of Rhodamine B. The results shows that the photocatalystprepared by hydrothermal method at pH=7 and Ag₃PO₄/BiPO₄ composite ratio at 4 :3 has the best catalytic performance. The degradation rate of rhodamine B reaches 61% after 180 min reaction, which is 27% higher than pure phase BiPO₄. The samples are characterized by XRD, SEM and ultraviolet-visible diffuse reflection (UV-Vis DRS), which indicates that the bandgap width of catalyst decreases, the more monoclinic type of BiPO₄ increases and the efficiency of photo-generated electrons and holes become lower. All of these properties canimprove the activity of degradation Rhodamine B.