The Yarlung Tsangpo Grand Canyon in southern Tibetan Plateau typically features incised bedrock and wide braided rivers. Yet, a recent discovery of two unique meandering streams within a young floodplain Cuoka offers insights into the formation of meandering rivers. Within the Cuoka floodplain, stratified layers of silty clay and root soil composite of 1.56m are deposited on the original lateral moraine basin. The sedimentation can be related to the damming of the floodplain’s mainstream, the Parlung Tsangpo River, in 1950s’ that backwaters the floodplain while promoting deposition of fine particles. This study highlights the primary factors behind the formation of these meandering streams: floodplain formation, valley slope leveling, cohesive deposition with dense riparian vegetation, and meandering initiation due to alternate bars or local discontinuities. Notably, the main and tributary streams within the floodplain exhibit distinct geometric and morphological features (topography, wavelength, curvature) that suggest different formative causes.