With climate warming, Glacier Lake Outburst Floods (GLOFs) are increasingly threatening people and property, which has been intensively studied worldwide. This paper takes the Himalayas region of China as the study area, where the GLOFs have frequently occurred during the past decades. The 143 potentially dangerous glacier lakes were first identified by six indexes in the study area. Then, the probabilities of three types of possible breaching modes (i.e. ice avalanche, glacier slide, ice-core melting) were quantitatively graded on the basis of the criteria of the probabilities of moraine-dammed lake breaching modes. Breach probabilities of the 143 potentially dangerous glacier lakes were further calculated by means of decision-making trees methods.