Moniliformin is highly toxic to animals. It can be detoxified by treating with Ozone (O3). The structure of moniliformin treated with O3 was analysed by means of IR and NMR spectrum etc. It was proved that the double bond was disappeared and the 4-C ring structure was opened. The structure of the two products are 1,2-dihydroxy-1,2-dicarboxyl-epoxyethane and 2-carbonyl-3-hydroxy-dibutyric acid. The experiment of toxicity comparison between moniliformin and its analogous material squaric acid was made using one-day age Beijing Ducklings by oral applying both medicines at dosage of 8mg/kg and 24mg/kg body weight separately. The result showed that squaric acid had no toxic to animals though its dosage was as three times as that of moniliformin. Author concluded that H in moniliformin is the key factor of its toxicity.