Abstract: With the gradual saturation of offshore wind power resources construction, the expansion of the wind power industry into far offshore has become an inevitable trend for future development. Far offshore wind power resources transmission in urgent need of high-voltage, large-capacity DC submarine cable, this paper calculates and analyzes the feasibility of ±640 kV DC submarine cable centralized delivery program, through the DC insulating materials research and verification, key production process research and test development, solve and verify the ultra-high-voltage DC submarine cable production process problems, to carry out flexible DC submarine cable at 90 ℃ under the load capacity calculations and analyzes the machine test validation. Through material selection, technical study and test development, the company successfully developed ±640 kV large cross-section DC submarine cable, and verified the reliable stability of ±640 kV large cross-section DC submarine cable through tests.