B ₂O ₃/HZSM-5 catalyst was prepared by multiple impregnation, and used as a catalyst for synthesis of diethanolamine from anhydrous liquid ammonia and epoxyethane in a continuous fixed bed operation. Effect of boric acid amount on pore size and volume of the catalysts was studied and found that optimum B ₂O ₃ content is about 3%. Meanwhile, the reaction conditions are optimized and listed as follows: molar ratio of anhydrous liquid ammonia/epoxyethane 10∶3, reaction temperature 60 ℃, reaction pressure 1.0~3.0 MPa and volumetric space velocity 1.5 h ^-1. Under these conditions, the yield of diethanol amine could be reach 56%.