Abstract: Fluoroacetic acid had been reported to be a strong schistosomicide in inhibiting the aconitase of Schistosoma japonicum. This article reports the preliminary results of studies on the antischistosomal mechanism of fluoroacetamide.Six to eight hours after an oral dose of fluoroacetamide 400μg/d the accumulation of citric acid in the worms became evident. In the meantime, the worms began to shift to the host liver. The maximum level of accumulated citric acid observed in the treated worms was about six times higher than that in the control worms when the drug was given successively for three days.Determination of the contents of glycogen, protein, lipid and nucleic acid of the worms during drug treatment showed that several changes occurred in different ways and obviously lasted long after the cessation of treatment. When the drug-treated worms were incubated in vitro in glucose containing saline, the ratio of the production of lactate to utilization of glucose (L/G) of the worms decreased.The existence and the role of the tricarboxylic aeid cycle in Schistosome japonicum were discussed.