In　this　work,　the　high-performance　and　flexible　solid-state　supercapacitors　were　fabricated　based　on　poly(vinyl　alcohol)(PVA)/NaCl/glycerol　hydrogel　electrolyte　and　activated　carbon　electrodes.　A　novel　assembling　method　was　proposed　according　to　the　formation　properties　of　PVA/NaCl/glycerol　hydrogel　electrolyte.　PVA/NaCl/glycerol　hydrogel　electrolyte　could　be　quickly　formed　in　a　short　time　at　room　temperature.　Thus　the　PVA/NaCl/glycerol　solution　was　coated　onto　the　activated　carbon　electrodes　and　the　hydrogel　electrolyte　was　in　situ　formed　on　the　surface　of　the　activated　electrodes.　Meanwhile,　the　PVA/NaCl/glycerol　hydrogel　electrolyte　could　retain　outstanding　flexibility　and　ionic　conductivity　at　a　low　temperature,　which　makes　the　solid-state　supercapacitor　have　excellent　low-temperature　tolerance.　Thus,　the　electrochemical　measurements　of　the　assembled　supercapacitor　were　performed　at　room　temperature　and　a　low　temperature　of　−23　°C,　respectively.　The　flexible　supercapacitor　can　show　an　outstanding　flexibility　and　electrochemical　performance　at　−23　°C.　Its　specific　capacitance　can　remain　approximately　81.0%　of　its　initial　specific　capacitance　at　room　temperature　and　the　capacitance　retention　could　keep　90.5%　of　the　initial　capacitance　retention　at　−23　°C.　It　also　could　be　anticipated　that　this　multifunctional　flexible　supercapacitor　with　the　PVA/NaCl/glycerol　hydrogel　electrolyte　would　have　broad　applications　in　modern　flexible　energy　storage　device.　©　2019　Elsevier　Ltd