In the leaching process the valuable element is transferred from the solid phase into the liquid phase via a leachate solution. Heap leaching is one of the most common leaching methods in the large scale. The safe performance of the leaching process is largely dependent on the heap stability. What happens in the large (macro) scale of the heap is directly or indirectly depended on the processes happening in the small (micro) scale. Predicting the state of the heaps after leaching improves the design and management of the overall structure of the heap. The main goal of this research is to have a better understanding of the mechanical behavior of the heaps before and after the utilization. In this regard, the coupled f chemo-hydro-mechanical process involved in the field of the heap 4 of Sarchesmeh Mine is modeled using the numerical and experimental methods. The results of experiments conducted on the heap soil before and after the simulated leaching process indicates that the soil grains density and size decreases. While the grain size distribution doesn’t change significantly. The results of the direct shear tests on the leached test samples indicated a decrease of about 4.6 degrees in the internal friction of the soil. After conducting the experiments, the accumulation and the leaching of the soils in the heap and their effect on the stability were modeled using PFC 2D in the 2D state. increasing the layers and their height in the steep beds increases the possibility of instability. In the current situation of heap 4 of Sarchesmeh Mine(at a height of 4.5 m) in the bed dip of 14% there is a significant decrease in the angle of repose of 2 nd and 3 rd layers. The situation of 2 nd and 3 rd layer of the heap in the height of 6.5 m and the bed dip of 8% indicates a decrease of 1:2.5 to 1:3.5 angle of repose. In the bed dip of 14% and the height of 6.5 m 2 nd layer is considered to be critical. After finishing the leaching of 4 layers in in the bed dip of 14% and the height of 10 m the 2 nd layer slips. It seems that the leaching in small scale and in the lower height layers doesn’t have a destructive effect on the heap stability. Increasing the height and the number of layers while increasing the bed dip makes the stability a critical issue.