A quick-release and quick-installation nut includes a nut body. The nut body includes a first threaded block and a second threaded block. An inner wall of the first threaded block and an inner wall of the second threaded block are formed with inner threaded surfaces for cooperating with an outer threaded surface of a screw rod. A right end of the first threaded block is detachably connected to a right end of the second threaded block. A left end of the first threaded block is hingedly or detachably connected to a left end of the second threaded block. The nut can realize quick disassembly and installation with the screw rod.