To　improve　the　surface　properties　of　recycled　fine　aggregates　(RFAs),　it　is　better　to　replace　natural　aggregates　for　the　preparation　of　ultra-high-performance　concrete　(UHPC).　The　feasible　modification　method　of　RFA　carbonization　after　being　soaked　in　nano　calcium　hydroxide　(nano-CH)　solution　(ICRFA)　is　investigated.　Untreated　RFA　(URFA)　and　carbon　dioxide-treated　RFA　were　the　control　groups.　The　results　revealed　that　the　pores　of　RFA　were　filled　by　calcium　carbonate　(CaCO3)　generated　from　the　carbonization　of　nano-CH.　The　total　porosity　and　the　contents　of　harmful　pores　and　multi-harmful　pores　of　UHPC　were　reduced.　Furthermore,　the　effective　water-binder　ratio　(w/b)　of　UHPC　with　RFA　was　higher　than　that　of　UHPC　with　ICRFA.　Therefore,　the　compressive　strength　of　UHPC　with　ICRFA　at　28　days　was　significantly　higher　than　that　of　UHPC　with　URFA.　The　modification　method　of　ICRFA　is　a　more　effective　and　economical　method　for　improving　compressive　strength　than　that　of　CO2-treated　RFA　(CRFA).