Abstract: The aim of this study was to synthesize 1-(5-(hydroxymethyl)-4-methyl-3-oxo-3, 4-dihydro-pyrazin-2-yl)guanidine(mucunaguanide), a pyrazinone alkaloid compound extracted from the seed of Stizotobium cochinchinensis. Starting from benzyloxy acetaldehyde, following four steps in reaction including condensation, cyclization, substitution and hydrogenation reaction, mucunaguanide was synthesized with total yield of 27. 9%, and purity of more than 97. 5%. Structures of all the intermediates and target compound were confirmed by IR, ¹H NMR and MS. This synthetic process was characterized with raw materials available, simple in operation with much milder reaction conditions, and was an ideal method of synthesis of this compound.