Bed-load　streaky　structures　are　typical　bed　morphological　features,　yet　its　formation　mechanism　remains　unclear.　To　fill　this　knowledge　gap,　flume　experiments　were　conducted　to　quantitatively　identify　the　characteristics　of　turbulent　coherent　structures,　sediment　particle　movement,　and　bed　surface　structure.　An　innovative　workflow　was　established　that　combines　the　particle　tracking　velocimetry　method　with　the　Kalman　filter　algorithm,　specifically　for　identifying　the　trajectories　of　sediment　particles　on　the　bed　surface.　Feature　matching　velocity　was　applied　to　acquire　the　flow　surface　field　and　structure-from-motion　(SFM)　was　used　to　reconstruct　the　three-dimensional　bed　topography.　All　the　flow　velocity,　sediment　movement,　and　bedforms　show　streaky　features　in　the　streamwise　direction　at　0.　068　＜　Θ　＜　0.113,　and　the　streaky　structures　gradually　fade　away　at　Θ　＞　0.113.　The　instantaneous　turbulence　properties　of　turbulent　flow　and　sediment　movement　in　the　spanwise　direction　disappear,　and　fixed　time-averaged　streaky　structures　are　formed.　The　streaky　structures　have　larger　characteristic　scales　(width　and　spanwise　distance)　in　the　middle　of　the　channel　than　those　near　the　sidewalls.　The　spanwise　distance　between　adjacent　streaky　structures　remains　about　twice　the　whole　flow　depth.　Finally,　this　study　proposes　a　formation　mechanism　based　on　fluid-sediment　interactions,　offering　innovative　measurement　and　analysis　methods　that　can　significantly　contribute　to　understanding　these　interactions.　©　2024　American　Society　of　Civil　Engineers.