The utility model discloses a flexible and composite seepage-proofing layer on an upstream surface of a high arch dam. The layer is internally provided with an inner layer protection layer painted with GB plastic sealing glue or adhered with a GB plastic sealing plate, and is externally provided with polyurea elastic bodies sprayed on the GB plastic sealing plate so as to form an outer layer protection layer which is wholly sealed on the inner layer protection layer. In order to prevent partial dropping or bubbles of the composite seepage-proofing layer which is internally provided with the inner layer plastic sealing plate and externally sprayed with the polyurea elastic bodies, polyurea elastic bodies with the width of 30cm are directly sprayed on the dam at the intervals of 5m in the height direction, and in middle of each dam section in the horizontal direction so as to divide the composite seepage-proofing layer. In order to prevent the periphery of the layer from tilting and the water seepage of the layer, the periphery of the layer is sealed by polyurea elastic bodies with single components. With the structure, the layer can be applicable to the condition that when the distress of concrete is expanded by 8mm, the high arch dam is not subjected to seepage under the action of a water head of 300m, so that the whole seepage resistance, crack resistance and durability of the upstream surface of the high arch dam can be improved, and the danger of hydraulic fracture due to the cracking of the surface of a dam body facing to water can be avoided so as to further improve the safety of the dam body.