Through the selection of 3 kinds of organic corrosion and scale inhibitors, and 3 kinds of biocide, the corrosion and scale problems of formaldehyde circulating water system treated with chemical method are studied. The production practice shows that it not only obtains obvious effect in the aspect of corrosion and scale inhibition, but also reduces the water consumption greatly through the technological conditions, which mix rate of organic composite water treatment chemicals of TS 609 to HEDP is 1 ∶ 2 and sodium dichloroisocyanurate to JN 2 is 1 ∶ 1, concentrating times is 3.5, Q_M to Q_R is 8.3%, Q_B to Q_R is 6.3%, all concentration of corrosion and scale inhibitor in water is 12 mg/L and so on, are adopted in circulating cooling water system of formaldehyde process.