Abstract: 2 barrier lakes formed on the Jinsha River in Tibet due to twice landslides of bank slope at Baige village in Oct. and Nov. of 2018. Firstly we analyze the landslide cause and the formation process of the barrier lake, then we study some characteristic values of the barrier lake such as structure, morphology, development of dam breaking and dam breaking stages, and these characteristic values were compared with the ones of previous dams. The investigation shows that the barrier body is mainly composed of fine particles, and proportion of coarse particles is larger on the surface and downstream of the barrier body. The poor erosion-resistant, storage volume, incoming flow and material composition are the main factors influencing the peak flow, and the incoming flow, erosion resistant of dam material and path length of the break section are the key factors for dam breaking duration.