A novel ternary Ag/Ag2CO3/BiVO4 plasmonic heterojunction photocatalyst was successfully fabricated by a precipitation method over BiVO4, followed by light reduction. The obtained composites were characterized by various measurements and the photocatalytic performances of the as-prepared composites were assessed by the degradation of tetracycline (TC) under visible-light illumination. The ternary plasmonic heterojunction photocatalyst exhibits higher and wider absorption in the visible and ultraviolet regions than the pure BiVO4 and it displays superior performance in the degradation of tetracycline. The highest efficiency of Ag/Ag2CO3/BiVO4 photocatalyst to degrade TC is up to 94.9% at 150 min. On the basis of the obtained experimental results, the probable photocatalytic mechanism of the enhanced activity is discussed. The degradation of tetracycline is not only influenced by (OH)-O-center dot, but also caused by valence-band holes (h(+)). Therefore, the improved photocatalytic activity of Ag/Ag2CO3/BiVO4 is due to the enhanced absorbance under the visible light, the facilitated charge transfer and the inhibited recombination of electron-hole pairs. The likely degradation pathway was proposed on the basis of the intermediate products detected by GC-MS. Moreover, the surface plasmon resonance and the electric field enhancement were simulated by the three dimensional finite difference time domain (FDTD) method.