A series of lanthanum modified-Ni/HY bifunctional catalysts for n-octane hydroconversion were prepared by ion-exchange method, and the influence of lanthanum contents on the activity and the selectivity was investigated. Py-FTIR and CO-DRIFTS results indicated that the addition of lanthanum could adjust the acidity and the metal state over Ni/HY catalyst, and consequently change the ratio of metal to acid functions. It was found that the best catalytic performance at the lanthanum exchange of ca. 8 wt.% was due to the suitable metal/acid ratio.