The invention discloses a detachable looseness-preventing bolt or screw 
assembly. The detachable looseness-preventing bolt or screw 
assembly comprises a bolt, a pawl 
gasket, a pressure pad nut and a 
ratchet screw nut or a 
ratchet screw cap, wherein the bolt, the pawl 
gasket, the pressure pad nut and the 
ratchet screw nut or the ratchet 
screw cap are matched with one another. A plurality of elastic pawls are arranged on the end face of the pawl 
gasket. The bolt comprises a screw nut and a screw rod. A radial annular 
flange is arranged at the end, close to a fastened object, of the ratchet screw nut or the ratchet 
screw cap. A ratchet structure is arranged on the end face, close to the fastened object, of the annular 
flange. An external thread matched with an internal thread of the pressure pad nut is arranged on the outer circle face of the annular 
flange. The ratchet structure on the annular flange is matched with the elastic pawls, so that the pawl gasket is prevented from rotating relative to the ratchet screw nut or the ratchet screw cap. An annular table board makes contact with the pawl gasket and abuts against the fastened piece, and thus the phenomenon that the ratchet structure suffers from pressure to be damaged is prevented. The detachable looseness-preventing bolt or screw 
assembly is reasonable in structural design, simple in structure, good in fastening performance and convenient to dismount and 
mount.