In order to avoid the electric corrosion of digging pile foundation near the grounding electrode of HVDC power transmission line, the insulation construction method for digging pile is researched. According to the requirement of Xiluodu-Guangdong ±500 kv double-circuit DC transmission line project, the insulation construction process between the foundation and the transmission tower, also between the earth and the digging pile foundation are introduced. Then, the reparation work of insulating foundation construction, the construction machines and tools, the requirements of construction material, the matters demanding attentions and the problems solved in the course of construction are introduced in detail. When the insulation construction is completed, the field detection results show that the foundation has been well insulated. The insulation construction technology can be a reference to the insulation design and construction of digging pile foundation of other DC power transmission projects.