Supercritical　water　gasification　of　coal　is　a　clean　and　efficient　coal　conversion　technology　with　great　development　prospect.　In-depth　study　of　flow　and　heat　transfer　characteristics　in　the　reactor　is　of　great　significance　to　the　design　and　optimization　of　the　reactor.　Based　on　Euler-Lagrange　method　and　coupled　with　chemical　reaction　kinetic　model,　a　three-dimensional　transient　CFD　model　of　coal-supercritical　water　fluidized　bed　reactor　for　hydrogen　production　was　established　in　this　paper.　The　characteristics　of　flow　and　heat　transfer　in　the　reactor,　the　distribution　of　particles　and　the　transformation　rule　of　product　components　were　studied.　The　numerical　results　provide　the　convective　and　radiative　heat　transfer　coefficients　of　coal　particles　respectively,　and　reveal　the　influence　mechanism　of　particle　size　on　the　coal　conversion　rate　from　the　prospect　of　heat　transfer.　©　2020,　Science　Press.　All　right　reserved.