A new photocatalyst was synthesized by heterojunction of commercial CoFe2O4 with P25. The degradation of sulfamethoxazole (SMX) with the photocatalyst under UV 350 nm was investigated. The effects of initial target compound concentration, catalyst dosage, and solution pH on the decay performance of SMX were studied. On the basis of the kinetics data, the pseudo-first-order rate constant of SMX decay becomes predictable by using a proposed model in terms of [SMX](0) and catalyst dosage. Light attenuation was found and analyzed by a linear correlation between k and transmission via a common factor (i.e., the catalyst dosage). The photocatalyst was found to be stable within the pH range of 5.2-8.8. The photocatalyst was proved to be easily separated and recycled, and the photocatalytic activity of the recycled catalyst remained intact after extensive reuse, suggesting that the CoFe2O4/TiO2 is a stable and highly efficient catalyst with good potential in real applications.