Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) ferroelectric thin films have been widely used in many areas due to the outstanding piezoelectric and electromechanical properties. Although many studies have been operated on the properties and applications of PMN-PT films, few researches focused on the domain growth dynamics of these materials. In this paper, the domain growth dynamics of PMN-PT thin films were investigated using piezoelectric force microscopy. The shape and the size of the artificial domains were imaged and calculated to depict the relationship between the imposed pulse voltage and the domain behaviors. A linear relationship between the pulse voltage and the domain size could be obtained before the saturation of polarization. Meanwhile, the domain size and the duration show the logarithmic relationship, and such domain growth dynamics were explained according to previous theories.