A plasma-catalytic system was constructed by coupling multi-needle corona discharge with Ag/TiO2 nanocatalyst. The discharge characteristics of the plasma-catalytic system were diagnosed, and the characterization of the Ag/TiO2 nanocatalyst was also performed. The multi-needle corona discharge coupling Ag/TiO2 nanocatalyst system was applied to remove low-concentration toluene from the air. The secondary pollutant of ozone was monitored during toluene removal. Further, the mechanism of toluene removal and suppressed ozone generation during toluene removal was disclosed. It was found that the plasma diffused in the whole discharge region when the discharge voltage was higher than 7.0 kV. The presence of Ag/TiO2 nanocatalyst showed no obvious influence on the discharge. These features facilitated the high plasma density and intimate interaction between reactants, plasma, and Ag/TiO2 nanocatalysts. Ag particles in the Ag/TiO2 nanocatalyst possessed an average size of 6.5 nm, which created large numbers of highly active Ag-TiO2 interfacial sites and endowed Ag/TiO2 nanocatalyst with strong absorption ability for UV-visible light. At a voltage of 7.5 kV, the multi-needle corona discharge obtained toluene conversion and CO2 selectivity of 21% and 7%, respectively. Coupling of multi-needle corona discharge and Ag/TiO2 nanocatalyst made toluene conversion and CO2 selectivity increased to 83% and 61%, respectively. The concentration of ozone in the plasma-catalytic system was 0.02 mg/m3, which had a remarkable decrease compared with the pure discharge (5.12 mg/m3). The performance of the multi-needle corona discharge coupling Ag/TiO2 nanocatalyst system was attributed to the synergetic effect between the light field, electrical field, and catalytic sites, which could modulate the conversion path of intermediates and extend the avenues of toluene removal. This study would provide an important reference for the application and development of plasma-catalysis techniques in indoor air purification.