Consider the general cubic di erential system x_ = P(x; y), y_ = Q(x; y), where P;Q 2 R[x; y], max fdeg P; degQg = 3 and GCD(P;Q) = 1. According to [1], we can construct a Darboux rst integral for a cubic di erential system, if this system has suciently many invariant straight lines considered with their multiplicities. In [2] we showed that there are exactly 26 canonical forms of cubic di erential systems which possess invariant straight lines of total multiplicity at least seven (including the invariant straight line at the in nity) along one direction. In this paper, using qualitative methods for dynamical systems, we investigate the systems obtained in [2] and show trajectories behavior on the Poincare disk.