Long-term cross-pollination has produced considerable heritable variation within and between populations of the tea plant and related species, resulting in a high level of genetic diversity. A good understanding and management of this pool of genetic resource diversity is of vital importance to tea plant improvement, since it directly affects the potential for genetic gain through selection. This chapter provides an overview of genetic diversity of tea plant, and its characterization and utilization. The chapter examines the origins and global distribution of tea cultivars, assessing the current status of tea genetic resources. The chapter explains the processes of tea germplasm evaluation and characterization and examines the exploitation and utilization of genetic diversity, looking ahead to future research trends in the area of ensuring tea’s genetic diversity.