The glacial debris flows along Palong River is large and frequency. Tianmo gully is a primary tributary on the left bank of Palong River. Glacial debris flows broke out many times in history, repeatedly blocking the river and forming a 1.5 km-long barrier lake. The frequency and volume of glacial debris flows is of great significance to the disaster prevention and reduction in mountainous areas. Based on the method of dendrochronology and the analysis of damaged tissue, growth inhibition and release of tree rings, the temporal-spatial distribution of debris flow events in the past 60 years is reconstructed. From the intensity of tree growth disturbance, the inundate area of debris flow and gully erosion process are discussed. The relationship between the occurrence time of debris flow and daily rainfall and temperature is further analyzed by Wit index. The results show that debris flows broke out in 1965, 1970, 1976, 2007, 2010 and 2018; The growth release and inhibition of tree rings lag behind the debris flow event for 1-3 years, and is directly proportional to the debris flows volume.