Catalytic activity, stability and selectivity of USY zeolite catalyst for alkylation of benzene with 1-dodecene were investigated using a continuous fixed bed high pressure microreactor. It is found that the catalytic activity and stability depend closely on the pretreatment temperature of catalyst and reaction conditions. The best result was obtained at 120 ℃ and 3.0 MPa with 8 molar ratio of benzene to 1-dodecene, and 4 h(-1) weight hourly space velocity of reactant over the catalyst with the pretreatment temperature of 500 ℃. Under this condition, the reaction conversion was nearly 100% and no deactivation was observed within the employed 50 h of time on stream with the selectivity of 2-phenyldodecene being 22%.