Ultra-high specific surface area porous carbons with micropores and narrow mesopores are preferred candidates for catalysis, pollution remediation, and energy storage. In this work, porous carbon materials derived from Milkvetch Root residue with specific surface area exceeding 3300 m 2 g −l was synthesized by controlled variable strategy. As electrode materials, the prepared ultra-high specific surface area porous carbon provides a specific capacitance up to 274.8 F g −l at the current density of 1 A g −l and maintains 224.5 F g −l at 50 A g −l . Moreover, the effects of activation conditions on the surface area, pore structure and electrochemical performance of the porous carbon materials were clarified. This work provides the direction for the design and construction of ultra-high surface area porous carbon with hierarchical structures for supercapacitor application.