Basalt　fiber　and　nano-silica　were　used　to　improve　the　recycled　concrete　in　order　to　improve　the　elevated　temperature　performance　of　recycled　concrete.　The　changes　of　mass　loss　rate　and　cubic　compressive　strength　of　modified　recycled　aggregate　concrete　after　25,　200,　400　and　600　were　tested　by　means　of　the　elevated　temperature　heating　and　compressive　strength　test.　The　microstructure　of　the　modified　recycled　aggregate　concrete　after　the　elevated　temperatures　was　analyzed　by　the　scanning　electron　microscopy　and　X-ray　diffraction.　Results　show　that　the　mass　loss　rate　increases　with　the　increase　of　temperature.　The　compressive　strength　and　the　optimum　mass　fraction　of　nano-silica　decrease.　The　mortar　matrix,　the　performance　of　interface　transition　zone　and　the　bonding　performance　between　the　fiber　and　the　matrix　deteriorate,　and　the　mass　concentration　of　CH　crystal　and　C-S-H　gel　decreases.　The　mass　loss　rate　increases　with　the　increase　of　the　replacement　ratio　and　the　nano-silica　mass　fraction,　the　compressive　strength　decreases,　and　the　mortar　matrix　is　loose.　Results　show　that　the　compressive　strength　and　microstructures　of　recycled　aggregate　concrete　are　seriously　affected　by　the　temperature,　replacement　ratio　and　nano-silica　mass　fraction,　while　the　basalt　fiber　dosage　has　no　significant　effect　on　the　compressive　strength　and　microstructures　of　recycled　aggregate　concrete.　Copyright　©2020　Journal　of　Zhejiang　University　(Engineering　Science).　All　rights　reserved.