The　central　contribution　of　the　current　paper　is　to　establish　a　practical　and　effective　reusable　garbled　circuit　scheme　with　parallel　updates,　where　each　update　is　applied　to　the　circuit　in　parallel.　First　of　all,　we　present　a　strengthened　notion　of　inner　product　functional　encryption　(IPE)　called　simulation-based　security　(SIM-security)　for　multi-instance　and　show　that　a　secret-key　IPE　scheme　is　multi-instance　SIM-secure.　Then　we　put　forward　a　reusable　garbled　circuit　scheme　based　on　the　IPE　scheme.　The　idea　is　a　reduction　from　re-randomizable　garbled　circuits　in　which　the　distribution　of　the　original　garbled　circuit　is　computationally　indistinguishable　from　the　re-randomized　garbled　circuit.　Finally,　we　implemented　reusable　garbled　circuits　and　validate　the　practicality　of　our　reusable　garbled　circuit　scheme.　Experimental　results　demonstrate　that　our　reusable　garbled　circuit　scheme　is　suitable　for　a　wide　range　of　real-world　scenarios.