Stone forest (‘Shilin’ in Chinese) is a unique karst landform with a complex evolution process. Based mainly on the characteristics and interrelationships of sub‐soil, soil and sub‐aerial erosion in Lunan karst area, the authors develop a triplex erosion model to describe the evolution of stone forest, and apply it to examine the current development stage and the prospect of the Lunan Stone Forest. The study shows that sub‐soil corrosion, a basic driving force for the vertical scope of a stone forest, usually occurs within 10 m below ground surface but is observed to be most active within the top 2 m, which constitutes the best development zone for stone forest. Under modern climatic conditions, the tip of the stone pillars in Lunan karst area is lowering at a rate of 10·4 mm ka−1, whereas the base of the stone pillars is deepening at 26·17 mm ka−1. Therefore, the height of stone pillars is increasing at a rate of 15·77 mm ka−1. Considering that soil erosion in the study area is as high as 650 mm ka−1, the visible height of the stone forest is actually increasing at a rate of 639·6 mm ka−1. However, the best evolution time for Lunan Stone Forest has already passed despite the fact that it is still growing taller at the present time. This is because the soil layer, which plays an extremely significant role in the heightening of stone pillars, is rapidly thinning at a rate of 623·83 mm ka−1. Copyright © 2006 John Wiley & Sons, Ltd.