The invention discloses a method for preparation of ethylene by ethanol dehydration. The method involves at least two catalyst beds, i.e. a catalyst A and a catalyst B. The catalyst A is composed of: an active component heteropoly acid, an assistant boron oxide, and a carrier silicon dioxide coated alumina, and the catalyst B consists of: an active component heteropoly acid ammonium salt, an assistant boron oxide, and a carrier silicon oxide. According to the invention, the two catalysts are employed for mutual cooperation to give full play to respective advantages, so that the reaction system has improved comprehensive reaction performance, and has higher activity, selectivity and stability.