The utility model discloses a dynamic vibration-damping boring cutter used for processing deep holes. The boring cutter comprises a boring bar and a cutter head (6) arranged at one end of a bar body of the boring bar; the boring bar mainly comprises the bar body (1), elastic positioning pieces (2) and cylindrical vibration-damping blocks (3); a cylindrical hole cavity is formed at the cutter head end where the bar body is arranged; two cylindrical vibration-damping blocks are designed; each cylindrical vibration-damping block is arranged at the center of the cylindrical hole cavity of the bar body by the two ends through the elastic positioning pieces; and the axial distance between the two vibration-damping blocks is not smaller than 10mm. Compared with a single vibration-damping boring bar in the prior art, the built-in double vibration-damping boring bar disclosed by the utility model greatly improves the vibration-damping performance, has good vibration-damping performance, greatly improves the boring hole processing conditions, and increases the work piece processing accuracy.