Abstract: At present, solid state decoupling devices with an isolation voltage of -2 V/+2 V are often used in pipeline AC drainage protection. However, under dynamic DC interference, the pipeline potential will seriously shift in the negative direction, which may lead to negative conduction of the solid state decoupling device and introduce DC stray current. Research had found that under dynamic interference, there was indeed negative conduction current in the solid-state decoupling device, and after negative conduction occurred in the pipeline, the cathodic protection potential of the pipeline could not meet the requirements, and the pipeline was subject to dynamic DC interference. Increasing the negative conduction threshold of the current collector could significantly reduce the negative current.