Researches　on　solids　mixing　and　segregation　are　of　great　significance　for　the　operation　and　design　of　fluidized　bed　reactors.　In　this　paper,　the　local　and　global　mixing　and　segregation　characteristics　of　binary　mixtures　were　investigated　in　a　gas-solid　fluidized　bed　by　computational　fluid　dynamics-discrete　element　method　(CFD-DEM)　coupled　approach.　A　methodology　based　on　solids　mixing　entropy　was　developed　to　quantitatively　calculate　the　mixing　degree　and　time　of　the　bed.　The　mixing　curves　of　global　mixing　entropy　were　acquired,　and　the　distribution　maps　of　local　mixing　entropy　and　mixing　time　were　also　obtained.　By　comparing　different　operating　conditions,　the　effects　of　superficial　gas　velocity,　particle　density　ratio　and　size　ratio　on　mixing/segregation　behavior　were　discussed.　Results　showed　that　for　the　partial　mixing　state,　the　fluidized　bed　can　be　divided　into　three　parts　along　the　bed　height:　complete　segregation　area,　transition　area　and　stable　mixing　area.　These　areas　showed　different　mixing/segregation　processes.　Increasing　gas　velocity　promoted　the　local　and　global　mixing　of　binary　mixtures.　The　increase　in　particle　density　ratio　and　size　ratio　enlarged　the　complete　segregation　area,　reduced　the　mixing　degree　and　increased　the　mixing　time　in　the　stable　mixing　area.　(c)　2022　The　Chemical　Industry　and　Engineering　Society　of　China,　and　Chemical　Industry　Press　Co.,　Ltd.