Abstract: High-lift device noise has been identified as a major noise source during aircraft approach and landing. Reviews on the noise generation mechanism and noise control methods of the high-lift device noise are conducted. Challenges in understanding the physical mechanism of the noise generation and implementing effective noise control has been pointed out. We performed high-fidelity large-eddy simulations for flow past the slat, flap trailing-edge and flap side-edge separately. Based on phase-averaging analysis, proper orthogonal decomposition (POD), dynamic mode decomposition (DMD), and two-point correlations, we increase insights on the underlying physics of the high-lift device noise. The results are expected to guide the design of high efficient noise control approaches.