Based on the improved delayed detached eddy simulation (IDDES) and the Ffowcs Williams-Hawkings (FW-H) acoustic analogy method, a numerical study was conducted on the aerodynamic noise characteristics of a vertical axis wind turbine (VAWT) with a near-wall cylindrical airfoil adopting active control. The results show that the near-wall cylindrical structure effectively suppressed blade boundary layer flow separation and significantly reduced pressure fluctuations at monitoring points in the wake region. As the tip speed ratio increased from λ = 1.68 to λ = 3.08, the system dynamic response time was significantly shortened from 2.14 s to 1.16 s. At a low tip speed ratio (λ = 1.68), the near-wall cylindrical airfoil effectively reduces noise in the mid- and low-frequency bands. At a moderate tip speed ratio (λ = 2.50), a significant full-band noise reduction is achieved, with a maximum reduction of 13.8 dB at monitoring point A at 500 Hz. When the tip speed ratio further increases (λ = 3.08), its suppression effect on high-frequency noise weakens. Further analysis of the sound field directivity indicates that at a moderate tip speed ratio (λ = 2.50), the near-wall cylindrical airfoil obviously optimizes the circumferential noise distribution of the VAWT. The sound radiation mechanism exhibits a transition from monopole-dominated to dipole-dominated as the tip speed ratio increases.