In　this　work,,　the　investigation　mainly　focused　on　the　synergistic　effect　of　phosphorus-containing　polyol　(BHPP)　and　nitrogen-containing　polyol　(MADP)　in　improving　the　flame　retardancy　Of　EG/rigid　polyurethane　foam　(RPUF).　BHPP　and　MADP　were　synthesized　through　dehydrochlorination　and　Mannich　reaction,　respectively.　The　influence　of　the　weight　ratio　of　BHPP　and　MADP　was　studied　by　thermogravimetric　analysis　and　limiting　oxygen　index　(LOI)　tests.　The　results　demonstrated　that　the　optimal　weight　percentage　of　BHPP　and　MADP　in　flame-retarding　RPUF　was　1/1.　In　addition,　the　incorporation　of　expandable　graphite　(EG)　into　the　RPUF/BHPP/MADP　system　could　greatly　improve　the　flame-retardant　properties　of　RPUF　composites.　When　the　content　of　EG　was　15　wt　%,　LOI　value　of　RPUF　composites　reached　33.5%.　Furthermore,　the　value　of　the　peak　of　the　heat　release　rate　was　reduced　by　52.4%　compared　to　that　of　pristine　RPUF.　Based　on　the　analysis　and　discussion,　a　condensed　flame-tetardant　mechanism　was　primarily　proposed.