Understanding the mechanisms of ecosystem services trade-offs and synergies is critical for forest management. Plant functional traits provide an approach to identify the relationships between forest structure, processes, and ecosystem services, and to explain the trade-offs and synergies among ecosystem services. We performed a systematic literature review of forest ecosystem services trade-offs and synergies from the perspective of plant functional traits based on 216 articles. The number of associations varied greatly in terms of both traits and ecosystem services. 51.9% were associated with leaf traits, while the most associated services were soil fertility (16.7%), biomass (15.7%), and carbon sequestration services (14.7%). Plant functional traits (15.4%) associated with individual services tended to have stable positive or negative relationships with those services, but most plant functional traits (84.6%) were associated with multiple ecosystem services. Trade-offs existed primarily between regulating services (runoff control, pest control, carbon regulation, invasion control, air quality regulation, and soil conservation) and material production services (biomass, soil water content, sediment buffering of mass movement, and wind protection), and synergies mainly existed within regulating and material production services. The 41 plant functional traits that had a substantial influence on ecosystem services trade-offs or synergies corresponded to five different ecosystem structures or processes (belowground structure, aboveground structure, material decomposition, material production, and nutrient capture). These empirical findings contribute to our understanding of trade-offs and synergies among ecosystem services, and have the potential to provide effective strategies for forest restoration and management.