Plant functional traits provide an effective way to investigate the complex relationship between biodiversity and ecosystem services. Many empirical studies have revealed the importance of plant functional traits for ecosystem service delivery, but there is still a lack of general understanding of the relationship between plant functional traits and ecosystem services. Here a systematic analysis was performed to investigate the effects of plant functional traits on forest ecosystem services and their trade-off/synergy relationships based on 216 references by using meta-analysis and bipartite network analysis. Among plant functional traits, leaf functional traits are the most concerned, accounting for 48.0% of the studied plant functional traits. Biomass, soil fertility, biocontrol, and carbon sequestration are the most in-depth studies in ecosystem services. About 81.8% of plant functional traits have stable relationships (positive or negative) with forest ecosystem services, and the unstable relationship is mainly concentrated in the ecosystem services associated with multiple plant functional traits, such as biomass, carbon sequestration, soil water content, soil fertility, and herbivory and biocontrol. In forest ecosystem, six trait-service clusters are determined, namely, water-cycle-related cluster, soil-conservation-related cluster, material-production-related cluster, disaster-control-related cluster, nutrient-cycle-related cluster, and pollination-related cluster, which reveal the relationships of trade-offs or synergies among forest ecosystem services. The key plant functional traits influencing these trait-service clusters were also identified. This study generally clarifies the research of the relationships between plant functional traits and forest ecosystem services, and reveals the influence direction and intensity of plant functional traits on forest ecosystems. The results can provide a scientific basis for understanding the formation mechanism of forest ecosystem services and coordinating the trade-off relationships of forest ecosystem services.