The Ni-doped PMN-0.1PT (PMN-0.1PT-xNi) relaxor ferroelectric ceramics were prepared by two-step columbite precursor method, and the effects of Ni dopant on the phase structure, dielectric, ferroelectric and electrostrictive properties were systematically investigated. The introduction of Ni dopant significantly improved the densification and grains size in the ceramics, but also profoundly modified the phase structure. It demonstrated that the substitution of Ni dopant for B-site in PMN-0.1PT lattice could affect electrical properties of PMN-0.1PT binary ceramics. Properly increasing the amount of Ni dopant led to the enhancement of dielectric and ferroelectric and remarkably increased the electrostrictive response. Results in this study indicated that at a composition x of 2.0 mol%, a large strain response could be obtained with maximum strain as high as 0.11% under the low field of 15 kV/mm at room temperature.