The enhanced (EDA) H-mode features high energy confinement together with the absence of edge localized modes (ELMs) and impurity accumulation, making it highly attractive for fusion reactors. The EDA H-mode has been observed recently in the HL-3 tokamak. This regime exhibits high energy confinement (), and without the occurrence of large ELMs. The EDA H-mode is achieved at a relatively high edge safety factor () and high plasma triangularity (), where the upper triangularity () is found to be essential. A distinct quasi-coherent mode (QCM) with a frequency of 20 kHz is detected in edge density and temperature fluctuations during the EDA H-mode phase. The QCM has a poloidal wavenumber of ∼ 0.4 cm−1, a radial wavenumber of ∼ 0.2 cm−1, and propagates in the ion diamagnetic drift direction in the plasma frame. Bispectral analysis shows strong nonlinear interactions between the QCM and broadband turbulence in the pedestal region. By regulating the pedestal particle transport, the QCM limits the growth of the edge plasma pressure gradient, thereby maintaining an ELM-free state in EDA H-mode.