This chapter explores the luminescence properties of InGaN/GaN nanowire quantum dots, focusing on the modulation mechanisms related to surface and localized states. Surface states are found to significantly impact luminescence efficiency, and surface passivation with ultra-thin dielectric films like silicon nitride and aluminum oxide effectively reduces surface state density, mitigates band bending, and enhances electron-hole wavefunction overlap. These improvements lead to stronger fluorescence, a noticeable blue shift in emission wavelength, and a boost in internal quantum efficiency by approximately 88%. Techniques such as ultraviolet photoelectron spectroscopy and time-resolved photoluminescence further confirm the positive effects of surface modulation on band structure and carrier recombination. Additionally, the Localized-State Ensemble (LSE) model is used to quantitatively analyze localized state emission. Surface treatments, including wet chemical etching and aluminum oxide passivation, significantly alter carrier distribution within localized states, influencing fluorescence peak shifts with temperature. The LSE model provides insights into how the relative energy difference between carrier filling levels and the density of states center dictates fluorescence behavior. In conclusion, strategic surface passivation and localized state engineering enhance the luminescence of InGaN/GaN nanowire quantum dots, laying a strong foundation for their use in high-efficiency optoelectronic devices like LEDs, micro/nano lasers, and single-photon sources.