In　order　to　improve　the　performance　of　oil-immersed　transformer　and　explore　working　characteristics　of　internal　temperature　field　and　flow　field,　a　multi-physical　field　coupling　method　based　on　eddy-temperature-flow　field　is　proposed　and　an　internal　fluid-heat　transfer　calculation　model　of　oil-immersed　transformer　is　established　in　this　paper.　Finite　difference　method　(FDM)　is　used　to　calculate　eddy　current　field　in　transformer.　Lattice　boltzmann　method　(LBM)　is　used　to　calculate　temperature-flow　field　of　transformer.　On　the　macro,　the　method　realized　solid-liquid　boundary　heat　transfer　with　the　units　of　kelvin.　On　the　mesoscopic,　the　method　was　used　to　calculate　the　temperature　transfer　and　oil　flow　in　solid　domain　and　insulating　oil　fluid　domain　with　the　units　of　dimensionless　LBM　molecular　distribution　function.　By　this　method,　fluid-solid　temperature　coupled　heat　transfer　based　on　macroscopic-mesoscopic　unit　scale　variation　was　calculated,　and　the　operating　characteristics　of　temperature　field　and　flow　field　in　oil-immersed　transformer　were　analyzed.　This　paper　designed　a　transformer　flow-heat　transfer　simulation　experiment　to　verify　the　proposed　model.　It　is　shown　that　since　the　iteration　of　LBM　algorithm　requires　the　diffusion　lattice　density　to　cover　the　calculation　area,　the　temperature　rise　is　not　obvious　at　the　early　calculation　stage　and　cannot　effectively　fit　the　operating　characteristics　of　the　internal　temperature　field　and　flow　field　of　the　oil-immersed　transformer.　After　a　certain　number　of　iterations,　the　calculation　error　is　within　5%　and　can　effectively　fit　the　transformer　operating　characteristics.　This　algorithm　model　has　some　engineering　significance　to　prevent　the　internal　fault　of　oil-immersed　transformer　and　reduce　the　internal　overheating　accident　of　oil-immersed　transformer.　©　2020,　Electrical　Technology　Press　Co.　Ltd.　All　right　reserved.