The invention provides an anti-seepage membrane assembly, a construction method of an underground waterproof curtain and an underground waterproof curtain, wherein the anti-seepage membrane assembly comprises a frame, an anti-seepage membrane body, a first joint and a second joint, wherein the anti-seepage membrane body is arranged in the frame; a first edge and second edge of the anti-seepage membrane body both extend to the outside of the frame; the first edge and the second edge are opposite; the first joint is in sealing connection with the first edge of the anti-seepage membrane body; thesecond joint is in sealing connection with the second edge of the anti-seepage membrane body; the first joint and the second joint are both of a spiral structure; and the spiral structure of the first joint is suitable for being embedded in the spiral structure of the second joint. In the process of forming the underground waterproof curtain, different anti-seepage membrane assemblies are splicedby using the spiral structures, so that the contact area between anti-seepage membranes can be increased, and the joint tightness during splicing of different anti-seepage membranes is ensured.