Both Bi12TiO20 and Bi12TiO20/Co particles were synthesized by a hydrothermal process. The as-synthesized particles were characterized by SEM and TEM for size and morphology, and the results showed the particles presented hierarchical morphology with the size of ~200nm. Both XPS and XRD results confirmed the existence of both Bi12TiO20 and Co phases in the Bi12TiO20/Co particles. The photocatalytic performance of the as-synthesized particles was investigated in Rhodamine B degradation reaction under visible light irradiation. Bi12TiO20/Co composites showed higher photocatalytic performance than single phase Bi12TiO20 particles, which could be attributed to the increased separation effects between photo-induced electrons and holes from. Meanwhile, the magnetic properties of Co could be used to magnetically separate and recycle the Bi12TiO20/Co composites after reactions. The stability testing experiment with Bi12TiO20/Co particles showed that the composite had a high stability over photocatalytic corrosion. The photoelectrochemistry investigation showed that the introduction of Co could increase the electron/hole separation efficiency in BTO/Co composites during photocatalytic reactions. This research proposed an effective and inexpensive way to increase the performance and recycling of Bi12TiO20 based photocatalysts.