The　dynamic,　heterogeneity　and　complexity　make　cloud　platform　much　less　credible.　As　a　vital　level　in　cloud　computing　platform,　IaaS　is　very　important　to　improve　the　trustworthy　degree　of　cloud.　In　this　paper,　we　explore　this　area,　we　identify　the　fundamental　function　provided　by　the　trusted　IaaS,　we　identify　the　indispensable　tasks　completed　by　the　trusted　IaaS,　and　then　we　propose　a　foundation　framework　for　establishing　trusted　IaaS.　Finally,　we　gave　a　conclusion　and　the　direction　of　future　works.