Abstract: The large-scale development of offshore wind power in deep and distant seas imposes higher demands on flexible DC transmission technology, among which high-frequency harmonic oscillation issues have become a critical bottleneck constraining the safe and stable operation of flexible DC systems. Taking the Rudong ±800kV/1100MW offshore wind power flexible DC grid-connected project as the research object, this study systematically analyzes three oscillation mechanisms: insufficient virtual damping of 2000Hz characteristic harmonics, impedance characteristic deviation at 320Hz, and excessively high 5/7th harmonic content on the wind farm side. It innovatively proposes a multi-dimensional coordinated suppression strategy of "virtual damping reconstruction—harmonic feedforward filtering—coordinated engagement of wind turbine soft filters." Engineering practice demonstrates that this strategy effectively eliminates high-frequency protection trip risks, avoids power generation losses, and provides a replicable and scalable technical paradigm for similar offshore wind power flexible DC projects.