The corrosion and hazard effects of DC earth electrode on adjacent buried oil and gas pipelines are becoming increasingly prominent, and more accurate calculation methods are urgently needed. On the basis of previous research, the equivalent circuit model of pipeline and grounding device is established by moment method, and the polarization effect at the damaged surface of pipeline is considered as a non-linear controlled voltage source. A calculation method considering the non-linear polarization effect of DC earth electrode on the surface of buried metal pipeline is proposed. In the rectangular tank of grounding Laboratory of UHV AC test base, the scaling test model of HVDC earth electrode and oil and gas pipeline is built to carry out experimental research. The validity of the calculation method proposed in this paper is verified. The results show that the calculation method is in good agreement with the test results, and it can provide an estimation reference for engineering application.