Abstract: Endemism describes the phenomenon that the distribution of individual species/taxa is critically restricted to a specific region. Seed plant genera endemic to China (endemic genera) are those with their main geographic distribution range within the borders of China. The geographic patterns of endemic genera can not only guide conservation planning, but these organisms are also important biological resources. We gath-ered data of 173 localities on environmental and spatial factors, and regional seed plant genera richness (GRN), endemic genera richness (EGRN) and endemic genera ratio (EGR), which was calculated by dividing EGRN by GRN. Multiple regression and variance partitioning were used to examine how environmental and spatial variables affect GRN, EGRN, and EGR. Our results showed that: (1) EGRN and EGR had stronger spatial variability than GRN, with highest values (richness and ratio) in central China and lower near national borders and continental edges. GRN exhibited an evident latitudinal gradient. (2) EGRN and EGR were mainly determined by habitat heterogeneity and spatial factors. Regional theoretical EGR was constrained by its geographical location, and was further adjusted by habitat heterogeneity (topographical complexity) and climatic factors. Geographical patterns of GRN, on the other hand, were mainly determined by climatic con-ditions and habitat heterogeneity rather than spatial factors. (3) Seed plant genera endemic to China could be rather difficult to define, and probably reflected inadequate information on phylogenetic evolution of local flora. Further studies are needed to examine the variance explained by spatial factors through a phylogenetic lense. Finally, flaws in the definition and classification of seed plant genera endemic to China were dis-cussed. Theoretically, genera endemic to China should not be defined according to the political borders. But, in practice, nearly all the lists of seed plant genera endemic to China proposed by several authors were based on the relationship between the geographic distribution of specific genus and national borders. Thus, we recommend that, the concept of seed plant genera endemic to China should be used carefully in both theo-retical research and biodiversity conservation practices.