The　self-microemulsifying　delivery　system　was　fabricated　by　whey　protein　isolate　(WPI),　daidzein　(Dai)　and　surfactants,　the　interaction　of　WPI,　Dai　and　D-α-Tocopherol　polyethylene　glycol　succinate　(TPGS)　was　hereby　studied　in　the　absence　or　presence　of　Tween　20.　The　increase　of　surfactant　concentration　led　to　the　decrease　of　the　modulus　and　changes　of　protein　interfacial　conformation,　which　allowed　the　formation　of　a　strong　intermolecular　network.　The　environment　and　structure　of　WPI　and　daidzein　could　be　changed　by　TPGS,　and　the　addition　of　Tween　20　could　further　enhance　the　interaction　between　the　components　by　changing　TPGS　structure.　With　the　increase　of　surfactants　and　oil　phase,　Ksv　and　Ka　values　of　WPI-Dai　increased　first　and　then　decreased.　Therefore,　the　interaction　between　the　components　was　also　dependent　on　the　WPI-surfactant　ration.　These　findings　provide　a　potential　strategy　for　designing　microemulsion　food　system　based　on　the　understanding　of　the　interactions　among　individual　composition　of　microemulsions.　©　2020　Elsevier　Ltd