Abstract: Supported Fe_(2/3)xNi_1-xSO₄-P₂O₅/γ-Al₂O₃ catalysts were prepared through impregnation and used in the oligomerization of mixed C₄ olefins; the effect of preparation parameters and reaction conditions on their oligomerization performance was investigated in a high pressure fixed-bed microreactor. The results demonstrated that under 3.0 MPa, 100 ℃ and a volume space velocity of 2 h^-1, the conversion of olefins and selectivity to dimer reach 50.7% and 52.2%, respectively, over the catalyst with a preferable Fe loading of 0.7 mmol/g(γ-Al₂O₃)and Fe/Ni atomic ratio of 2. In addition, it was found that the interaction between γ-Al₂O₃ and SO₄^2-plays an important role in the efficiency of active sites.