The Ag/AgCl@BiOCl/Bi12O17Cl2 (Ag/AgCl@BOC) plasmonic composites have been successfully synthesized by anchoring Ag/AgCl nanoparticles on the surfaces of BiOCl/B12O17Cl2 nanosheets via a deposition-precipitation strategy at room temperature. The XRD, XPS, SME, TEM, UV-vis DRS, PL, Photocurrent, EIS, BET-BJH, and ESR were applied to explore the intrinsic microstructure and physicochemical properties. Furthermore, the in situ diffuse reflectance infrared Fourier transform spectroscopy is used to investigate the adsorption and photocatalytic reaction mechanism during the NOx oxidation process. The optimized 1:2 Ag/AgCl@BOC composites not only exhibited excellent photocatalytic performance (49.5%) but also displayed high photochemical stability for removal of NO at the indoor air level under visible-light irradiation. Based on the DMPO-ESR spin trapping, the active species generated from Ag/AgCl@BOC were O-center dot(2)- radicals and (OH)-O-. radicals under visible light. The results demonstrate that the synergetic effect of surface plasmon resonance of the Ag/AgCl nanoparticles and the effective carrier separation ability result in the improvement of photocatalytic efficiency. The present work can provide a facile strategy to the design of high and stable performance bismuth-based plasmonic photocatalysts for environmental purification.