Theheattransfermechanismofsilicaaerogelwasstudiedbyusingthekinetictheory.Basedonthefeaturesofthemicrostructureofsilicaaerogel,nanoporemodelwasbuilt.Theexpressionofthethermalconductivityofgas innanoporewasderivedwithtakingaccountoftheinteractionforceofmolecules.Thethermalconductivityofgasinsilica aerogelwasachievedwiththederivedexpression.Aheattransfermodelofsolidmatrixunitobtainedfromthestructure ofsilicaaerogelwasdeveloped.Accordingtothekinetictheory,theeffectivethermalconductivityofsilicaaerogelwas obtained.Theresultsshowthattheaveragegasmoleculefreepath,theinteractionforceofmoleculesandtheforcebetweenmoleculeandwallarethemajorfactorswhicheffectthethermalconductivityofgasinsilic aerogel,thediameters ofsolidmatrixunitandcontactinterfacearemainfactorsaffectingthethermalconductivityofsolidmatrixunit,thepore sizedistributionseriouslyaffectstheequivalentthermalconductivityofsilicaaerogel.