An Ag/AgFeO2/Ag3PO4 ternary was synthesized by hydrothermal method with polyvinylpyrrolidone (PVP). The composite materials were characterized by XRD, SEM, TEM, DRS and XPS. XRD, SEM and TEM results are used to characterize the structure and morphology of Ag/AgFeO2/Ag3PO4 samples, DRS results are mainly used to characterize the light absorption capacity of Ag/AgFeO2/Ag3PO4 samples. Photocatalytic results showed that the photocatalytic performance of Ag/AgFeO2/Ag3PO4 photocatalyst was significantly improved, which was 10.6 times than that of pure AgFeO2. The optimal photocatalyst can degrade MO (Methyl Orange) up to 98% in 1 h. Simultaneously, the cyclic experiments showed that it had good stability, from 80% for Ag/AgFeO2/AgPO4 to 58% for pure Ag3PO4 after five cycles. To obtain further insight into the high photooxidative activity of AgFeO2, ab initio density functional theory (DFT) calculations have also been carried out. The mechanism study shows that the synergistic effect of heterojunction and strong SPR of silver nanorods make the catalyst have higher photocatalytic performance and better stability.