Sealing quality directly affects the service life of the anode anodic oxidation coatings. For the anodic oxidation coatings intended for exterior buildings, the phosphoric/ chromic acid immersion with prior nitric acid treatment test method is specified as arbitration method in european standard. The effect of the prior nitric acid treatment on sealing quality test was studied. The results show that the prior nitric acid treatment has the action of dissolution and enlargement. The introduce of the prior nitric acid treatment in sealing quality test provides a more strict sealing quality test method, makes the sealing quality discrimination becoming more sensitive.