In　this　paper,　the　isogeometric　dual　reciprocity　boundary　element　method　(IG-DRBEM)　is　firstly　applied　to　solve　three-dimensional　(3D)　transient　heat　conduction　problems　in　functionally　graded　materials　(FGMs)　with　heat　sources.　Using　the　fundamental　solution　of　the　3D　potential　problem,　the　integral　equation　of　boundary-domain　is　established　by　the　weighted　residual　method.　The　normalized　temperature　is　introduced,　and　the　domain　integral　is　transformed　into　the　boundary　integral　by　the　dual　reciprocity　method　(DRM).　Finally,　the　theoretical　framework　of　the　isogeometric　BEM　for　FGMs　problems　is　established.　Furthermore,　the　effects　of　different　approximation　functions,　time　steps,　element　refinements　and　the　distance　from　the　inner　point　to　the　boundary　on　the　results　are　discussed　in　detail　via　several　examples,　which　verify　the　validity　of　the　presented　method.　In　order　to　promote　the　development　of　IGBEM,　the　program　code　of　this　article　can　be　obtained　by　sending　email　to　yubochina@hfut.edu.en.　(C)　2021　Elsevier　B　N.　All　rights　reserved.