Abstract: Polyploidy(or whole-genome doubling) is an important pathway for plant speciation, with existing angiosperms possibly occurring once or even multiple times. The traditional definition of polyploidization is that the number of chromosomes doubles relative to the ancestral group. The most commonly used research method for understanding polyploidy is karyotype analysis, which provides basic cytological parameters of the studied species, including chromosome number, ploidy level, karyotypic asymmetry, and karyotype coefficient of variation. At present, karyotype research has evolved from basic parameter analysis of species to multi-group/multi-disciplinary study, with an associated shift from lower taxonomic level (e.g., population, species, or family/genus) to higher taxonomic level research (e.g., tree of life). In addition, the integration of phylogeny and karyotypes will provide insightful evidence on the potential evolutionary characteristics and tendencies of karyotypes, and the cytological mechanism driving the evolution of plant diversity at the phylogenetic scale. Furthermore, exploring cytological features of the chromosome atlas or polyploidy at the regional or floral scale will help elucidate the influence of geo-ecological environmental shifts on chromosome ploidy. Additionally, constructing a regional chromosome atlas will shed light on the formation and evolutionary history of flora. Plant karyotype research provides new ideas for study on the origin and evolution of systematics, molecular phylogeny, tree of life, and floristic geography. As new methods are used in plant karyotype analysis and polyploidy, results on the effects and mechanisms will reveal the chromosomal evolution and cellular geographic features of plant groups and flora. Future trends in plant cytology research will be multi-disciplinary and integrate evidence from various research fields and will clarify the causes and significance of plant karyotype diversity at different levels to more fully understand plant species diversity and speciation.