Abstract: With the continuous improvement of living standard，people have paid more and more attention to health problems.In recent years，cases about food products soaked with formaldehyde and adding substances banned in food use，such as formaldehyde sodium bisulfate，made formaldehyde problems become focus of world's attention.At present，countries have yet formulated unified health standards about problem of formaldehyde in foods.In addition，combined with source of formaldehyde more extensive，its edible safety made more concern among the public.Formaldehyde is a carcinogenic and teratogenic substance.It is very important to correctly understand formaldehyde in foods.Aiming at the source of formaldehyde in foods from several aspects，formaldehyde content in food could been controlled by controlling endogenous formaldehyde in food，strengthening food hygiene supervision and management，reducing environmental pollution，and so on.Harm，source and preventive measures of formaldehyde in foods were summarized to better un