Based on existing literature, interactions between aboveground plant biomass and herbivorous insects have been well explored, however, there are still limited knowledge regarding the interactions between herbivores and fine root biomass (FRB). In this research, a one-year experiment was carried out at the community level across 16 temperate, subtropical, as well as tropical forests in China, so to investigate the impact of herbivores on FRB. To control fine root-feeding, the insecticide（Chlorpyrifos）was applied, and the biomass of fine roots was measured after grading them using the segment order-based classification method. According to the results, the application of insecticide significantly increased FRB, which exceeded that of the control plots by 18.34 %, 9.82 %, and 14.19 % in June, August, and October in the 16 forests, respectively, which indicates that herbivores are a key factor influencing FRB. By using the hierarchical cluster analysis method, the clustering of herbivorous feeding on fine root sites classified class 1-2 fine roots into one category, class 3 fine root into another, class 4 fine root into a separate one, and class 5 fine root into yet another. This classification is consistent with the division of absorptive fine root (AFR) and transport fine root (TFR) as defined by the root order hierarchy. Under insecticide treatment, the average growth rate of fine root biomass in classes 1-5 gradually decreased with increasing root order, at rates of 63.23 %, 36.53 %, 20.04 %, 12.17 %, and 8.83 %, respectively. The insecticide treatment mainly enhanced AFR biomass, while the increase in TFR biomass was less pronounced yet significant, suggesting that herbivores primarily affect AFR biomass, which is a crucial resource for these herbivores. In addition, the impact of insecticide treatment on AFR biomass varied among the 16 sites over different sampling times, indicating temporal and spatial differences in the influence of herbivores on AFR biomass. In June, the influence of insecticide on AFR biomass increased significantly as latitude decreased, and herbivores had a significant impact on AFR biomass mainly in the cold temperate, temperate, northern warm temperate, southern subtropical, and tropical regions of China. In August, herbivores had a significant impact on AFR biomass in all temperature zones. In October, herbivores had a significant impact on AFR biomass in all climatic zones except the cold temperate zone. This experiment is the first to explore the impact of herbivores on FRB on a large scale in China. These findings have significant implications for a deeper understanding of belowground processes in forest ecosystems, aboveground-belowground carbon allocation patterns, forest carbon budgets, and sustainable forest management. Simultaneously, this research is also of great reference significance for more accurate estimation of forest below, namely, ground net primary productivity.