In this paper, we investigate the isolated closed orbits of two types of cubic vector fields in Double-struck capital R-3 by using the idea of central projection transformation, which sets up a bridge connecting the vector field X (x) in Double-struck capital R-3 with the planar vector fields. We have proved that the cubic vector field in Double-struck capital R-3 can have two isolated closed orbits or one closed orbit on the invariant cone. As an application of this result, we have shown that a class of 3-dimensional cubic system has at least 10 isolated closed orbits located on 5 invariant c...
