The invention discloses concrete for a railway switch base filling layer. The concrete is mixed by raw materials including 370 parts of cement, 180 parts of mineral mixtures, 44 parts of expanding agent, 866 parts of river sand, 738 parts of broken stones, 184 parts of water and 7.7 parts of polycarboxylic copolymer according to 1M3 filling quantity standard. When the railway switch base filling layer is poured, a leveling blanket and switch slabs are constructed according to a conventional method at first, a pouring mode by the aid of a pump truck, a transfer hopper and a chute is adopted, and each switch slab is poured at one step. As the concrete has excellent mobility and a self-filling performance, the concrete can pass through an engineering portion with compact reinforcements and the complex structural section, is dense in filling, does not segregate or leak water, and has high homogeneity, engineering quality is guaranteed, durability of a concrete structure is improved, the problem that pouring of vibration operation components is not easy to be applied or cannot be applied is resolved, pouring speed is improved, a construction process of the concrete structure is simplified, construction efficiency and construction quality are improved, and construction period is shortened.