The invention discloses a compound type perpendicular seepage-proofing screen which is used for preventing horizontal seepage of pollutants in soil or underground water. The compound type perpendicular seepage-proofing screen comprises a perpendicular flexible seepage-proofing part and a by-pass seepage preventing part, wherein the perpendicular flexible seepage-proofing part comprises a rectangular HDPE (high-density polyethylene) geomembrane; the by-pass seepage preventing part comprises a by-pass seepage preventing supporting part and self-hardening mud which coats the by-pass seepage preventing supporting part; the by-pass seepage preventing supporting part comprises gridding cloth and sodium-based bentonite encapsulated in the gridding cloth, and a groove is formed in the surface of the by-pass seepage preventing supporting part; the bottom of the perpendicular flexible seepage-proofing part is embedded and inserted into the groove of the by-pass seepage preventing supporting part, and the bottom of the perpendicular flexible seepage-proofing part is fixed with the by-pass seepage preventing supporting part through a bolt. The compound type perpendicular seepage-proofing screen has the advantages of being simple in construction, good in seepage-proofing effect, and the like, and can be used for solving the by-pass seepage problem on a joint of the HDPE geomembrane and an underground water-impermeable layer.