The invention provides a
coating composition, which comprises trivalent
chromium compounds, auxiliary filming agents, acid, dissoluble
zinc salt and water, wherein the amount of the acid meets the requirement that the pH value of the
coating composition is between 1 and 3. The invention also provides a preparation method of the
coating composition, which comprises the following step: uniformly mixing the trivalent
chromium compounds, the auxiliary filming agents, the acid, the dissoluble
zinc salt and the water, wherein the adding amount of acid meets the requirement that the pH value of the coating composition is between 1 and 3. The invention also provides a
zinc plating passivating material, which comprises a base material, a zinc plating layer and a passivating layer, wherein the zinc plating layer and the passivating layer are sequentially attached to the surface of the base material, and the passivating layer is a product obtained after the coating composition is dried. The passivating layer formed on the zinc plating material of the coating composition has the effect that the zinc plating material can also realize the
corrosion resistance for a long time without being coated with an antirust
oil film and has good attaching performance. The method of the invention omits the working procedures of coating and antirust oil removal, improves the production efficiency, saves the production time, and reduces the cost.