The distribution of earth surface potential（ESP） caused by the UHVDC project with the monopole ground return mode has negative impact on the AC system. In order to ensure safe and stable operation of the AC system

this paper modeled the actual distribution of soil around the UHVDC grounding electrode

and employs the traveling wave method and the image method to calculate the earth surface potential. The calculation program is coded with MAT-LAB to compare the regularities of ESP distribution in the horizontal double-layer model and the compound alpine soil model. The sensitive parameters affecting ESP are analyzed through changing the parameters of the compound alpine soil model. Results show that the current distribution via using the compound alpine soil model to calculate ESP is ba-sically consistent with the measured current value. And in the compound alpine soil model

the thickness and resistiv-ity of shallow soil and the alpine resistivity are more sensitive to ESP near the DC grounding electrode than the deep soil resistivity

and the buried depth of the DC grounding electrode and the alpine width are slightly sensitive.