Polarization curves of brass, dezincing-resistant brass and bronze were measured by channel flow double electrode (CFDE), and the electrochemical property of dezincing-resistant brass was investigated. By using CFDE, Cu(I) and Cu(II) ions dissolved from the copper-alloy electrode can be determined simultaneously during the measurement of polarization curve. The anodic polarization curve of brass was divided into two potential regions, namely, selective dissolution of zinc below 0 V vs. SSE (region I) and both dissolutions of copper and zinc above 0 V vs. SSE (region II). In the case of anodic polarization curve of dezincing-resistant brass ranked as type I by JBMA T303 test, the current was small in the region I, and the dissolution ratio of zinc was small in the region II. On the other hand, the corrosion test under the fresh water flow was carried out for brass, dezincing-resistant brass, bronze and SUS316. As the result, the dissolution morphology of dezincing-resistant brass ranked as type I tended to general corrosion even in the case that the brass showed the dezincing corrosion. In addition, the short circuit between the dezincing-resistant brass ranked as type I and SUS316 didn’t show galvanic corrosion since the corrosion potential of the dezincing-resistant brass ranked as type I is closed to that of SUS316 in the present test water.