The　purpose　of　this　study　was　to　investigate　the　regeneration　effect　of　waste　cooking　oil　(WCO)　on　aged　asphalt　with　molecular　dynamics　(MD)　simulation,　comparing　it　with　a　rejuvenator.　Firstly,　the　molecular　models　of　virgin　and　aged　asphalt　were　established　by　blending　the　four　components　of　asphalt　(saturate,　aromatic,　resin,　and　asphaltenes).　Then,　different　dosages　of　the　rejuvenator　and　WCO　(6,　9,　and　12%)　were　included　in　the　aged　asphalt　model　for　its　regeneration.　After　that,　MD　simulations　were　utilized　for　researching　the　mechanical　and　cohesive　properties　of　the　recycled　asphalt,　including　its　density,　viscosity,　cohesive　energy　density　(CED),　shear　modulus　(G),　bulk　modulus　(K),　and　elastic　modulus　(E).　The　results　show　that　the　density　values　of　the　asphalt　models　were　relatively　lower　than　the　existing　experimental　results　in　the　literature,　which　is　mostly　attributed　to　the　fact　that　the　heteroatoms　of　the　asphalt　molecules　were　not　considered　in　the　simulation.　On　the　other　hand,　the　WCO　addition　decreased　the　viscosity,　the　shear　modulus　(G),　the　bulk　modulus　(K),　and　the　elastic　modulus　(E)　of　the　aged　asphalt,　improving　its　CED.　Moreover,　the　nature　of　the　aged　asphalt　was　gradually　restored　with　increasing　rejuvenator　or　WCO　contents.　Compared　with　the　rejuvenator,　the　viscosity　of　the　aged　asphalt　was　more　effectively　restored　through　adding　WCO,　while　the　effect　of　the　CED　and　the　mechanical　properties　recovery　of　the　aged　asphalt　was　relatively　low.　This　implies　that　WCO　could　restore　partial　mechanical　properties　of　aging　asphalt,　which　proves　the　possibility　of　using　WCO　as　an　asphalt　rejuvenator.　Additionally,　the　MD　simulation　played　an　important　role　in　understanding　the　molecular　interactions　among　the　four　components　of　asphalt　and　the　rejuvenator,　which　will　serve　as　a　guideline　to　better　design　a　WCO　rejuvenator　and　optimize　its　content.