Abstract: Cantilever bank collapse is the dominant pattern in the peat-type meandering river of the Zoige basin in the Yellow River source region, but few previous studies were aimed at revealing this type of bank failure and its threshold conditions that determine the lateral migration rate of a meandering river. In this work, we apply a combination method of field measurement, theoretical model and numerical simulation to study the bank collapse process and its threshold conditions of a Ω-shaped bend in the upper Maiqu, a tributary of the Black River in the Zoige basin, focusing on the five cross sections of the bend where we take field measurements. A theoretical model of cantilever riverbank stability, namely BSTEM, is developed for this peat-type meandering river with composite bank layers of different soils, and static equilibrium equations are derived to describe cantilever tension failure and shear failure of the upper and lower layers. BSTEM is used to simulate the bank failure process of the silt layer at the five sections, and verified using the field-measured data of bank profile, bank soil composition, and hydrological parameters. We calculate the bank stability coefficient at a threshold collapse condition of the bank in flood period, and predict time changes in bank profiles at the five sections caused by three straight occurrences of bank failure, achieving a good agreement with measurements.