Abstract: The compressive performance of fiber reinforced polymer composites is closed associated with the mechanical properties of polymer matrix. In this paper, unidirectional laminates of CF-nano SiO₂/Epoxy multi-phase reinforced composites have been prepared using continuous carbon fibers(CF) and epoxy matrix with uniformly-dispersed SiO₂ nanoparticles. The systematic experimental study has been carried out. It shows that the incorporation of nanoparticles into matrix contributes to the considerable enhancement of compressive strength of fiber reinforced polymers. The compressive strength of composites is found to be increased by 62.7% with the nanoparticle vlume ratio to nano SiO₂/Epoxy of 8.7%. The reinforcing effects of nanoparticles have been theoretically analyzed based on the elasto-plastic micro-buckling model for unidirectional laminates. A method was proposed to construct the constitutive relation during compression for nanocomposite matrix through loading-unloading tests, according to the damage behaviors of epoxy matrix containing nanoparticles. The compressive strength of the prepared multi-phase reinforced composites can be well predicted by combining the classic elaso-plastic micro-buckling model and constructed constitutive relation of nanocomposite matrix. The experimental verification demonstrates the good agreement achieved between the predicted results and the measured data.