Abstract:The spatial variability of plant species richness was analyzed using geostatistics in the Karst area of Bijie, Guizhou Province, which presents wide altitudinal range in southwest China. The optimal semivariogram theoretical model fitted for arbor species richness was spherical model, and the linear sill model for shrub and herb. The arbor species richness was highly related to altitudinal gradient with a spatial heterogenous rate of 0.0052, which mainly affected by natural controlling factors with altitudinal variation. Shrub and herb species were mainly affected by random factors, which showed very weak relationship with altitudinal gradient and their spatial heterogenous rates were 3.15 and 34.55, respectively. The altitudinal range of arbor species richness was 177.37 m, which indicated a wide altitude range affected by random factors. The altitudinal range of species richness of shrub and herb were 73.02 m and 49.97 m, respectively, which indicated a narrow altitude range affected by random factors. The changes of Moran’s I index of shrub and herb species along altitudinal gradient were similar that were different from that of arbor species.