Abstract: When high voltage direct current (HVDC) grounding electrode operates under unipolar mode, water in soil near the anode will decrease due to the electric osmosis effect, and the resistivity and temperature will increase sharply. In order to find out the characteristic of electroosmosis effect of the soil near HVDC grounding with coke bed under different current density, an electroosmosis experiment platform was designed. The soil electroosmosis experiment was carried out under different current densities, and the moisture and temperature of each measuring point were monitored. The results show that when the current density is under 10 A/m², the water content near the anode decreases rapidly within the first 100 minutes, and then decreases slowly to a stable level after 100 minutes. But the soil resistivity and temperature will increase sharply when the current density reaches 20 A/m². According to the limitation index of current density of 1 A/m² in the current international standard, some relaxations of requirements should be considered.