In order to investigate the effect of ZnO nanoparticles (ZnONPs) on soil ecosystem in soil with added cellulose and lignin, five treatments were set up: cellulose, cellulose + ZnONPs, lignin, lignin + ZnONPs, and no addition. The soil respiration, microbial biomass, and the activities of soil enzymes were explored during a 56-day incubation time after the addition of ZnONPs. The results showed that when cellulose and lignin were added to the soil, the CO2 efflux increased by 90.9% and 18.2%, respectively, compared with the control soil. The microbial biomass carbon and the activity of peroxidase, polyphenol oxidase, β-glucosidase and cellulase were increased. Compared with the treatment with the addition of cellulose and lignin only, the exposure of ZnONPs increased the CO2 efflux, microbial biomass carbon, β-glucosidase and cellulase activities, but decreased the peroxidase and polyphenol oxidase activities. We concluded that the addition of cellulose and lignin to farmland soil increased respiration, microbial biomass and soil enzyme activity, but the degradation degree of cellulose was higher than lignin. The ZnONPs promote soil respiration, microbial biomass, and hydrolase activity throughout the culture period, but inhibited the activity of redox enzymes.