(1 − x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT, x = 0.2–0.4) ferroelectric (FE) ceramics were prepared by the partial oxalate route. The synthesized PMN-PT ceramics exhibit high density and densified microstructure although slight content of pyrochlore phase impurity exists. With the increase of PbTiO3 (PT) content, the phase structure of the PMN-PT ceramics changes gradually from rhombohedral perovskite structure, across the morphotropic phase boundary (MPB) composition and to tetragonal perovskite structure. The FE structural phase transition of PMN-PT changes gradually from the diffused ferroelectric phase transition (FPT) of typical relaxor FEs to nearly first-order FPT of normal FEs, confirmed by dielectric and FE properties measurements. The PMN-PT ceramics exhibit excellent dielectric and piezoelectric properties, and fully developed and saturated P–E hysteresis loops, in which the MPB effects are clearly shown by these electrical properties. The MPB composition of the PMN-PT system is determined locating at x = 0.31–0.33 by XRD measurement and electrical properties measurements.