The wastewater containing high concentration(5562.71mg/L) of nickel ion was first completely precipitated at pH 9, and subsequently treated by a ceramic microfiltration membrane with a pore diameter of 0.5μm. During the concentration process, the membrane flux(J) dropped significantly at the initial stage, then declined slowly, and finally decreased at a rapid rate again. The nickel rejection coefficient(R_Ni) was found to be approx. 1. When the volume concentration factor(VCF) increased from 1to 10, the nickel concentration in the retentate(C_r) increased from 5562.71 to 55507.76mg/L, whereas the nickel concentration in the permeate(C_p) remained nearly constant at approx. 13.26mg/L. Then, the complexation-ultrafiltration process was studied using the permeation fluid from the microfiltration process as the feed solution. Poly(ethylene imine) was employed as the complexing agent. The effects of the polymer/metal mass ratio(r_p/m), pH, temperature and operating pressure on R_Ni and J were investigated. Further, the process of ultrafiltration concentration was studied. The results showed that R_Ni increased with increasing r_p/m or pH and decreased slightly with temperature, and that the operating pressure exerted no effect on R_Ni; J increased with temperature or operating pressure. With increasing pH, J increased at first, and then reached a constant value. The effect of r_p/m on J was insignificant. The ultrafiltration concentration experiment was carried out at r_p/m=7 and pH=9. When VCF increased from 1to 30, J only declined by 9.76%. C_r increased linearly from 13.26to 396.64mg/L, whereas C_p remained roughly unchanged at about 0.04mg/L. Nickel ions were concentrated effectively, and the permeation solution from the ultrafiltration process was discharged directly.