Abstract: This paper focuses on the weathering decay characteristics of coal gangue in severe cold mine areas. These coal gangue are subjected to the treatments of content moisture,freeze / thaw cycles and content moisture+freeze / thaw cycles under laboratory conditions,respectively. The results show that the weathering decay rate under content moisture+freeze / thaw cycles treatment is higher than that under content moisture or freeze / thaw cycles. The hierarchical clustering method is applied to analyze the decay characteristics of the coal gaugue. The sample is almost individually clas- sified into two clusters. The result also show a significant difference in content moisture+freeze / thaw cycle groups. The existence of frost crystallization wedging brings the disintegration of coal gaugue decay rates. The results also show that the effect of moisture variation,but not freeze / thaw cycle,on rock decay is a crucial factor in coal gaugue decay. Freeze / thaw cycle,in particular,affects the coal gangue,because it causes more spalling and fracturing by frost crystal- lization. The analysis suggests that the moisture content and phase plays a key role in coal gaugue decay processes.