Detachable double-faced countersunk head fastener and connecting method and application thereof

The invention discloses a detachable double-faced countersunk fastener and a connecting method and application thereof, the detachable double-faced countersunk fastener comprises a countersunk screw and a countersunk nut which can be connected or detached, one end of a polished rod of the screw is connected with a screw head, and the other end of the polished rod of the screw is connected with an external thread section; the nut comprises a nut head and a polish rod with the inner side provided with a connecting inner threaded hole. The end face of the screw head close to the polish rod side and the end face of the nut head close to the polish rod side form a first pressure-bearing clamping face and a second pressure-bearing clamping face which are used for fastening a connected piece respectively. The polished rod penetrates through the connected piece and is suitable for being in threaded connection with the countersunk head screw and the countersunk head nut, and the polished rod is inserted into the throu