Many-lights rendering has always been an important research topic in computer graphics. It is one of the important methods to achieve global illumination effects, and it is a great demand in related industries such as games, movies, and animations, etc. However, efficient many-lights rendering is still a big challenge in both fields of off-line rendering and real-time rendering. This paper reviews the main progress of many-lights rendering methods in recent years. Among those many-lights rendering methods, their major goal is to improve the rendering efficiency. In the field of off-line rendering, we first review the algorithms of accelerating visibility test computation for reducing the average rendering time of a single light source. Then, we discuss light source clustering algorithms, and review accelerated rendering algorithms which are directly based on light source clustering. Different strategies for light source clustering are discussed, including strategies using hierarchical structures and strategies based on matrix analysis. After that, we review important sampling methods based on light clustering. In the field of real-time rendering, we introduce several rendering algorithms based on light culling. We also provide comparison and analysis of the advantages and disadvantages of various methods, and summarize the research trends and challenges of many-lights rendering.