Piperazine is used as a main ingredient of anthelmintics, used to treat intestinal roundworms infection in human and poultry and to treat pinworms by altering cell membrane permeability and causing hyperpolarization of the membrane. Piperazine is a main moiety in psychoactive drugs. Certain piperazine derivatives are suspected of ecstasy substitutes. The piperazine ring and piperazine derivatives are important cyclic components in industrial field as building blocks for hardener of epoxy resins, corrosion inhibitors, insecticides, accelerators for rubber, urethane catalysts and antioxidants. In this research piperazine was prepared by cyclization of ethylenediamine on ZSM-5. Catalyst zeolite HZSM-5 was modified with KCl, KNO3 and La(NO3)3. Study on the affect of the temperature, the input speed, the concentration of ethylenediamine, and the catalysis of the sepiolite with and without acid pre-treatment. Further more, the reaction parameters were optimized. The temperature was about 340ºC, the concentration of ethylenediamine was 50%, and the input speed was 0.02ml/min. Under above conditions, the conversion of ethylenediamine and the selectivity of piperazine were preferable. Based on the data analyzed, the zeolite HZSM-5 with La(NO3)3 modified selectivity of piperazine had preferable catalysis, while the conversion of ethylenediamine was about 80%, and the selectivity of piperazine was up to 75%. In the same condition, the catalysis of sepiolite in synthetic of piperazine was preferable, the conversion of ethylenediamine was up to 70%, the selectivity of piperazine was also desirable.