The stability of lanthanides (Ln) doped silicon cage clusters Ln@Si-16 has been proved by theoretical investigations. Particularly, fullerene-like Ln@Si-16 structures are always more stable than Frank-Kasper structures, which is different from transition metal doped Si-16 clusters. By taking into account the spin-orbital coupling (SOC), some of the Ln@Si-16 clusters maintain large total magnetic moments. The clusters with Pr, Nd, Sm and Tm have large orbital moments. We have provided the evidence to clarify the importance of the spin-orbital effect in Ln doped clusters, which may give useful information for further Stern-Gerlach magnetic deflection experiments and theoretical simulations. (c) 2012 Elsevier B.V. All rights reserved.