The semiconductor photocatalytic technology has been considerably studied due to its excellent catalytic performance in water pollution control. Herein, in this study, novel SrCoO3/Ag3PO4 composite materials with different SrCoO3 content were synthesized via a simple hydrothermal synthesis method. The characteristics of the as-prepared samples were detected through SEM/HRTEM, XRD, UV-vis DRS, PL, ESR, FT-IR, and XPS techniques, and then, the photocatalytic performance of SrCoO3/Ag3PO4 toward the degradation of tetracycline was investigated. When the mass ratio of SrCoO3 and Ag3PO4 in the composite was 1:1.5, the degradation rate constant of tetracycline in SrCoO3/Ag3PO4 (1:1.5) system is 0.0102 min(-1), which is 1.7 times that of the Ag3PO4, and 3.78 times that of the SrCoO3. In addition, reactive species were also analyzed through the free radical trapping experiment and DMPO spin-trapping ESR spectra analysis, showing that OH center dot, h(+), and O(2)(center dot-)participated in the catalytic degradation process of tetracycline to varying degrees. Finally, the photocatalytic mechanism of SrCoO3/Ag3PO4 was also proposed.