This study introduces a quantitative evaluation method for the lifecycle of electric hydrogen production in microgrids, considering line electric thermal couplers. By analyzing the operational mechanism and benefits of hydrogen production through residual electricity, we systematically evaluated the cost‐effectiveness of Proton Exchange Membrane electrolytic hydrogen production. A comprehensive lifecycle cost model was constructed, including equipment investment, maintenance, operating costs, and line thermocouple failure costs. By combining hydrogen sales, electricity consumption, new energy subsidies, and delayed construction benefits, a lifecycle benefit model was developed to measure economic performance. Experimental results showed that under a 5% power outage rate, the hydrogen distribution network has a short investment payback period, high production, and significant economic benefits, reaching 23.19 million US dollars by the sixth year. This study provides valuable insights for economic decision‐making in electric hydrogen microgrids.