Increasing attention has recently been focused on the linkages between plant functional traits and ecosystem functioning. A comprehensive understanding of these linkages can facilitate to address the ecological consequences of plant species loss induced by human activities and climate change, and provide theoretical support for ecological restoration and ecosystem management. In recent twenty years, the evidence of strong correlations between plant functional traits and changes in ecosystem processes is growing. More importantly, ecosystem functioning can be predicted more precisely, using plant functional trait diversity (i.e., functional diversity) than species diversity. In this paper, we first defined plant functional traits and their important roles in determining ecosystem processes. Then, we review recent advances in the relationships between ecosystem functions and plant functional traits and their diversity. Finally, we propose several important future research directions, including (1) exploration of the relationships between aboveground and belowground plant traits and their roles in determining ecosystem functioning, (2) incorporation of the impacts of consumer and global environmental change into the correlation between plant functional traits and ecosystem functioning, (3) effects of functional diversity on ecosystem multifunctionality, and (4) examination of the functional diversity-ecosystem functioning relationship at different temporal and spatial scales.