研究了已生成较厚锈层的带锈铸铁在３．５％ＮａＣｌ溶液中阴极保护被中断后的电位衰减规律．结果表明，其电位呈负指数关系衰减．带锈铸铁的阴极保护被中断后电位衰减相当缓慢，能较长时间地维持金属基体处于较负的电位范围．即阴极保护中断后较长时间内，带锈铸铁仍处于被保护的电位状态． The decay law of potential after the cathodic protection was interrupted in 3.5% NaCl solution with rust layer was studied. The results show that the potential decline in a negative exponential relationship. Cathodic protection with cast iron is interrupted after the potential attenuation is quite slow, longer time to maintain the metal substrate in the more negative potential range. That cathodic protection interrupted a long time, the rusty cast iron is still in the protected potential state.