As a heterogenous material, fiber-reinforcedcomposites (FRC) have a significant structural mechanism. The mechanical behaviour and failure machanism of FRC depend significantly on its meso-structure and the properties of each constituent. It is a new trend to study the relationship between the macro-mechanical behaviour and the properties of the constituents as well as the meso-structual parameters. In this paper, some developments in the mechanism of strengthening and toughening of FRC, mainly for fiber-reinforced concrete, are reviewed.In addition, the developing trends of this subject are discussed.