The stable equilibrium geometries, relative stabilities, and electronic and magnetic characteristics of Ren (n=2–16) clusters were investigated by density functional theory method. The calculated fragmentation energies and second-order differences of energies exhibited interestingly that the stabilities of Ren (n=2–16) clusters show a dramatic odd-even alternative behavior of the cluster size n: with the even-numbered Ren clusters being obviously more stable than their neighboring odd-numbered Ren clusters (beside n=11). Simultaneously, the calculated HOMO-LUMO gaps of Ren (n=6–16) display an oscillatory feature at large-sized Ren clusters. From the calculated magnetic moments and growth behaviors of Rhenium clusters, the magnetic Re6 unit can be seen as the building block for the novel magnetic cluster-assembled nanomaterial. Such calculated results are in good agreement with the available experimental measurements.