Doping Ni in Sr-2(Fe1-xNix) MoO6 (SFNMO) (0.00 <= x <= 0.20) significantly affects its magnetic behaviors. Having successfully synthesized the double perovskite structure using MoO2 as the starting material via a mechanical activation route, we have investigated the effects of Ni doping on the long-range B-site order and magnetic behaviors of (SFNMO), in which the long-range B-site order between B and B' cations is progressively enhanced by an increasing level of Ni doping. Accordingly, both magnetization and the Curie temperature of Sr2FeMoO6 are enhanced, where they both depend almost linearly on the degree of long-range B-site order.