[Objective] The formation conditions, initiation mechanism and dynamic characteristics of the glacial debris flow disaster occurred on September 10, 2020 at Zhibai gully in Linzhi City of Tibet, were analyzed in order to provide scientific reference for the early warning and risk prevention in the construction projects in Southeast Tibet. [Methods] The initiation process, erosion-sediment characteristics and destruction of the debris flow disaster were identified according to the field survey, remote sensing interpretation, observation, and monitoring. [Results] The drive force of the “9·10” debris flow was the high-altitude rock/ice avalanche. The formation process included three processes: ① Due to the seismic fracturing caused by the Milin earthquake in 2017, and freeze-thaw cycle of high level rock, a rock collapse was developed in the south watershed, triggering ice avalanche and forming ice-rock mass flow moving to the slope moraine platform, ② Ice-rock mass flow scraped slope moraine and loose soil materials, entered into the 2^# branch gully and carry soil material along the channel bed, amplified disaster scale. ③ Through the collision and friction in the process of movement, the ice undergoes phase changed and drove the ice-rock mass flow to debris flow. [Conclusion] The triggering conditions, water-soil coupling process and dynamics characteristics of the ice avalanche type debris flow are different from those of the other glacial rainfall complex type debris flow, and its dynamics parameters are influenced by the high potential energy at the initiation point and the ice-water phase change during the motion, which are very different from the results obtained by existing calculation methods. In the future, the existing methods for calculating the dynamic parameters of rainfall type mudflow cannot be directly adopted in the prevention and control of glacial mudflow disasters, and the dynamic parameters should be analyzed based on the initiation mechanism of mudflow.