A new 3-formaldoxime-Quinoxaline-N,N-dioxide-2-ethylformate has been synthesized by oxidizing reaction and condensation reaction.The structure of compound are characterized by IR,1H NMR,MS and elemental analyses.The bacteriostasis activity of new compound are assessed by 6 kinds indicative bacterium by disk diffusion method.The results show that the melting point,the molecular weight and the molecular formula of compound are respectirely 216~217℃,277.23g/mol and C12H11O5N3,and the compound has stronger activity against bacteria.