Through extending a model for size-dependent glass transition temperature (Tg), the size-dependent Curie temperature of low-dimensional ferromagnetic metals (particles, wires and thin films) with different morphologies in full size range (Tc) is modeled. Based on energetic and thermodynamic approaches, the critical size and morphology of the metals are considered. It is found that Tc drops as size decreases, which corresponds to the experimental results of Ni particles and wires, as well as Fe, Co and Ni thin films.