The invention discloses a method for building a water storage type landscape plant community. The method includes the concrete steps that landscape plants are divided into a high functionality level, a medium functionality level and a low functionality level according to the water storage capacity per unit area; the landscape plants at all the levels are planted in a planting area in a combined mode to form the multiple-layer mixed plant community, the multiple-layer mixed plant community comprises a horizontal structure and a vertical structure, according to the area ratio of 3:2:3, the planting area is divided into a rain water storing and retaining zone away from a boundary, a buffering and infiltrating zone located in the middle part and a runoff retardation zone close to the boundary by the horizontal structure in the direction parallel to roads and the water edge boundary, and the planting area is divided into an upper layer, a middle layer and a lower layer by the vertical structure. The water storage type landscape plant community built by the method can play a role in storing and retaining rain water and reducing overland runoff, and bring ecological benefits and the environmental function into play, and has the excellent landscape aesthetics function.