Forest fragmentation is threatening the health and survival of ecosystems though reducing species diversity and sustainability of the ecosystems. As an important plant-animal network, plant-rodent interaction plays a significant role in maintaining biodiversity and function of a forest, but their functional response to habitat patch size and succession stage is seldom investigated. Here, we monitored seed predation by small rodents in 15 forest patches with different sizes and at different stages of succession in a subtropical forest in Dujiangyan, Sichuan Province. Based on a new method integrating IR camera-monitoring with a seed tagging method, we measured species interaction strengths between seeds and rodents, and then illustrated the rodent-seed interaction networks of different patches, so as to analyze the influence of size of the forest patch and succession stage on parameters of the network. We found that rodent species richness was highest in medium patches (2-4ha.), and lowest in large patches (9-30ha.); Weighted-Interaction Nestedness Estimator (WINE) in secondary forests was significantly higher in the patches of late succession stage (20-40yrs) than that of early succession stage (10-20yrs); the total number and sum of diameter at breast height (DBH) of plants in the seed-rodent network was significantly higher in the primary forests than the secondary ones. Our results suggest that forest fragmentation showed some influences on WINE of seed-rodent network, but not on the other network parameters, which is probably due to the interaction generality of the seed-rodent network. This study provides a basis for further research on species interactions between trees and rodents, and the structure and function of the seed-rodent network.