Alkylation of toluene with tert-butanol was investigated over La2O3-modified HY zeolite catalysts in the microfixed bed reactor. The affect factors of conversion of toluene and the selectivity of tert-butyltoluene were studied. The main reaction products have been identified as p-tert-butyltoluene and m-tert-butyltoluene, La2O3 modified HY zeolite catalyst can significantly improve the selectivity of p-tert-butyltoluene. The result showed that 5% La2O3-modified HY zeolite catalyst was catalytic active (32.4% conversion of toluene), with para-selectivity near 82% at 473 K after 8 h. At the same time the catalysts were characterized by the X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The FT-IR results showed that the modifier could increase the concentration of weak B acid of HY zeolite and obviously improve the selectivity of p-tert-butyltoluene.