The liquid-phase alkylation of benzene with ethylene over a domestic modified zeolite catalyst was carried out in an integral micro-reactor. The effects of temperature, benzene to ethylene molar ratio and the weight hourly space velocity of ethylene on the catalyst performance were studied, respectively. And the appropriate operating conditions for ethylbenzene synthesis were decided as follows: temperature 190～220℃,benzene/ethylene molar ratio 6～8 and the weight hourly space velocity of ethylene≤2h^-1 under these conditions ,the ethylene conversion,thylbenzene selectivity were more than 99.0%,93% and 99.0%,respectively.The stability test of the catalyst was also carried out.The conversion of ethylene and the selectivity of ethylbenzene were not decreased with reaction time.It was indicated this type of modified zeolite catalyst has a good active stability.Under the condtions,the dimethylbenzene was not detected and the contents of other byproducts were very low.