The invention relates to the field of ship construction and particularly relates to a detachable anti-falling device which comprises bases and a cover body, wherein the cover body is rotationally arranged on the bases through rotating shafts, each base is provided with a clamping device, and each clamping device comprises a body as well as a clamping part, a fixing part and a clamping hole which are arranged on the body, wherein the clamping part and the fixing part are arranged oppositely, an axial line of the clamping hole points to the fixing part, and the clamping part is movably penetrated in the clamping hole. The detachable anti-falling device provided by the invention is detachably connected to a lightening hole through the clamping devices arranged on the bases, and the cover bodyis rotationally arranged on the bases; and the detachable anti-falling device can be quickly mounted on the lightening hole through the clamping devices, the safety of construction workers can be guaranteed, and the construction workers can pass through the lightening hole conveniently.