A　method　for　predicting　the　diffusion　behavior　of　rejuvenators　in　aged　asphalt　was　developed　based　on　free　volume　theory　to　avoid　the　influence　of　experimental　conditions　or　speculative　simulation　models　on　results.　Three　types　of　rejuvenators　(straight　saturate,　cyclic　saturate,　and　naphthene　aromatic)　with　different　molecular　structures　and　AAA-1　aged　asphalt　were　selected　to　verify　the　model.　According　to　the　prediction　of　diffusion　coefficients　of　typical　types　of　rejuvenators,　the　influencing　factors　of　the　diffusion　behavior　of　rejuvenators　were　comprehensively　analyzed.　The　results　show　that　the　prediction　method　can　predict　the　diffusion　coefficients　of　rejuvenators　in　aged　asphalt　and　avoid　experimental　error　through　standardized　methods.　The　diffusion　coefficient　of　the　rejuvenators　is　affected　by　the　interaction　of　temperature,　rejuvenator　dosage,　and　rejuvenator　type.　At　normal　temperature,　it　is　easier　for　the　naphthene　aromatic　to　diffuse　in　aged　asphalt　than　the　cyclic　saturate　and　straight　saturate.　The　increase　of　temperature　makes　the　saturate-based　rejuvenators　more　active,　and　the　cyclic　saturate　shows　the　highest　diffusion　coefficient　at　high　temperature.　A　similar　trend　occurred　when　the　rejuvenator　dosage　was　increased.　According　to　the　molecular　chemical　characteristics,　rejuvenators　with　small　or　light　molecules　have　the　advantage　of　diffusion　at　high　temperature,　while　at　normal　temperature,　it　is　recommended　to　select　the　rejuvenator　with　a　benzene　ring　structure.