Abstract: The horizontal zonal pattern of Theaceae p lant species richness in Guangdong Province and its relation to theenvironmental factorswere studied. Both data of species distribution and environmental factors were tabulated basedon a digitized map of Guangdong Province gridded at 0. 5°latitude ×0. 5°longitude. Grid2based richnesswasmappedusingDMAP, a distributionmapp ing p rogram, and horizontal patternswere assessed using F tests. The richness centerof the Theaceae p lant species under study is located in themountainous area of north Guangdong (22. 5°N, and 112～115°E). These p lants species exhibited significant longitudinal difference (P =0. 001 2) , and latitudinal variation (P=0. 004 9). Canonical Correspondence Analysis (CCA) showed the distribution of p lant species could be exp lainedby caloric factors and moisture factors, andMAMI (mean annualminimum temperature) was the key factor determi2ning the distribution pattern of Theaceae p lant species richness in the study area.