Abstract: The spatial effects of biomass on Pinus kesiya var. langbianensis forest, a endemic and dominant tree in Pu'er City, was analyzed, based on the forest resources survey and planning data of Pu'er city, and GIS environment, Local Indicators of Spatial Association (LISA), R language and GraphPad Prism. The results showed that: The biomass on P. kesiya var. langbianensis forest increased first and then decreased from west to east, and gradually increased from south to north. The global Moran's I index of the biomass on P. kesiya var. langbianensis forest was 0.436, which passed the 1% significance level test and showed a very significant spatial positive correlation, presenting an obvious aggregation distribution pattern. The high value aggregation (HH) of biomass accounted for the largest percentage (29.83%). It is mainly distributed in the central and northern areas of Pu'er City. The spatial heterogeneity level of biomass gradually increases with the increase of regional scale. Consequently, it is necessary to consider the influence of spatial effect when studying large-scale biomass problems. The study provided theoretical support for optimizing and adjusting the spatial structure of P. kesiya var. langbianensis forest and improving the service function of forest ecosystem, and enriching the application of spatial effect in forestry research which has certain typical and reference.