Abstract: The Reynolds number effect is one of the key factors for predicting the aerodynamic characteristics of advanced aircraft since it affects flight performance and development costs. This paper provides a comprehensive discussion of three major aspects of the Reynolds number effects of aircraft. Firstly, the advantages and limitations of different research methods in exploring the Reynolds number effect are introduced, with particular emphasis on large low-temperature wind tunnels as an effective way to obtain the aerodynamic characteristics of real flight Reynolds numbers. Secondly, the nonlinearity and complexity of high-Reynolds-number flow fields and their effects on aerodynamic characteristics are thoroughly analyzed. This analysis encompass diverse scenarios including slot flows around multi-element airfoils, shock-wave/boundary layer interaction over supercritical airfoils, high-angle-of-attack fighters, and inlet performance of flying wing configurations. Finally, correction methods for the Reynolds number effects are discussed, underscoring the importance of integrating wind tunnel experiments, numerical simulations, and flight tests. Based on a rigorous analysis of existing correction models' performance, insights are provided for developing more precise correction frameworks. In summary, the overview presented in this paper serves as a valuable reference for deepening our understanding of high Reynolds number effects, advancing the development of efficient simulation methods, enhancing aircraft design levels, and provides technical guidance for advanced aircraft development.