Abstract: Species of the genus Castanea are ecologically and economically significant woody plants. Historically, their genomic research has lagged due to inherent genetic complexities, including large genome sizes, high levels of heterozygosity, and a high proportion of repetitive sequences. In recent years, the rapid evolution of high-throughput sequencing, long-read sequencing, and three-dimensional (3D) genomics has catalyzed breakthroughs in both fundamental research and molecular breeding applications. This paper systematically reviews the recent progress in high-quality genome assembly, functional gene discovery, the elucidation of molecular mechanisms underlying key traits, and evolutionary analysis within the genus Castanea. We integrate and compare genomic characteristics, phylogenetic relationships, and speciation histories across various species, focusing on the molecular regulatory basis of biotic resistance, fruit quality formation, and environmental adaptability. Furthermore, the application of molecular breeding technologies in Castanea is summarized. Addressing current research bottlenecks, we discuss future frontiers such as precise pangenome construction, multi-omics integration, optimization of gene-editing technologies, and the implementation of conservation genomics. This review aims to provide a comprehensive theoretical foundation for the genetic improvement of Castanea germplasm and the sustainable development of the chestnut industry.