The invention provides a narrow valley narrow toe plate structure and a construction method. The downstream end of a toe plate is provided with a downward protruding structure, the downstream end of the protruding structure is connected with an anti-seepage plate, and a vertical seam waterstop is arranged between the protruding structure and the anti-seepage plate; the upper side of the downstreamend of the toe plate is connected with a reinforced concrete panel, and a peripheral seam waterstop is arranged between the toe plate and the reinforced concrete panel; a special cushion layer area is arranged between the reinforced concrete panel and the anti-seepage plate. During construction, the connecting position of the toe plate and the anti-seepage plate and the connecting position of thetoe plate and the reinforced concrete panel are fixedly provided with the waterstops, a formwork is erected, and concrete for the toe plate and the anti-seepage plate is poured and cured; after the strength of the concrete for the toe plate and the anti-seepage plate reaches the design strength, consolidation grouting is carried out on a toe plate and anti-seepage plate foundation and curtain grouting on the toe plate at the later stage is carried out; through the downward protruding structure at the bottom of the toe plate, the stone excavation and pouring construction amount of the toe plate foundation is reduced, the thickness of the toe plate is reduced, and the anti-slip performance of the toe plate is improved.