The invention provides a screw component which is not prone to falling off. The screw component comprises a screw and a screw cap; one end of the screw is flat; an annular sucking ring is arranged onthe left end of the screw cap; an elastic layer is arranged on the outer side of the sucking ring; a cover plate is arranged on the right end of the screw cap; a wire pulling hole is formed in one side of the cover plate; the inner side of the cover plate is connected with the sucking ring; an anti-corrosion layer is arranged on the outer side of the cover plate; the diameter of the right end of the screw cap is larger than that of the left end; according to the screw component which is not prone to falling off, on the basis of retaining basic functions of a screw, the screw cap is arranged onthe flat end; after assembly of the screw is finished, the screw cap is covered, so that the screw is filled and protected; the screw cap is difficult to disassemble, and the screw cap and a screw hole are flash with each other as far as possible, so that the screw component is safer; a matching effect is good; the sucking ring is arranged in the screw cap and can suck on the flat end, so that assembly is simple, and the screw component is not prone to falling off; meanwhile, the wire pulling hole is formed in the cover plate, so that operation is simple when the screw cap needs to be disassembled; flexibility is very high; and practicability is high.