The effects of amino-functionalized molybdenum disulfide (f-MoS2) on the curing activity and mechanical properties of epoxy-based composites were evaluated. The f-MoS2 was prepared through the mild reaction between mercapto-ethylamine and the exfoliated MoS2. Benefiting from the universal binding ability of amino groups, good dispersion of f-MoS2 in epoxy matrix was achieved. Studies of the curing behavior of epoxy composites showed that the curing temperature and heat release during the curing process of epoxy composites with MoS2 was lower than that of neat epoxy and composites with MoS2, indicating a decreased activation energy. The f-MoS2 containing amino groups on its surface was revealed can react with epoxy matrix and enhance the curing reactions like a co-curing agent of amine-type curing agent. The mechanical properties and thermal stability of the epoxy were both enhanced by f-MoS2. The storage modulus of the EP/f-MoS2 composites was about 60% higher than that of EP/MoS2 composites, which was attributed to the improved dispersion of f-MoS2 in matrix and the strengthened interfacial interactions between f-MoS2 with epoxy than that of the neat MoS2.