The electroplating of bright Zn-Ni alloy process using HEDP as coordinating agent, ZNP as additive agent is studied. The effect of coordinating agent, chloride content, [Zn2+]/[Ni2+], cathode current density, temperature, and supplementary coordinating agent on Ni content is investigated; composition and physical phase of alloy plating layer, brightness of plating layer, and stability of plating solution are comprehensive considered; and also, the optimum composition of plating solution for bright Zn-Ni alloy electroplating and technological condition is determined; finally, deposition mechanism is discussed.