A case of suspicious food poisoning caused by nitrite in some schools was reported at 14 o'clock on February 23，2010. The cause of the accident was judged as eating nitrite by mistake after epidemical，hygienic survey and examining surplus food samples. The victims were 32 employees of the school and their main clinical manifestations were dizziness，headache，vomit，nausea，cyanosis，palpitation and lack of strength. All subjects were cured by treatment with methylene blue，vitamin C，fluid infusion and other symptomatic treatment and were discharged after two days. It is suggested that nitrite is toxic for oral intake by accident. Propagation on the Food Safety Law should be enhanced in the relevant departments. The hygienic management system of schools should be perfected and the awareness of health knowledge in canteen staffs should be improved to prevent similar events from happening again.