A low-cost four-element system cementitious material, a preparation method and an application thereof are provided by the present disclosure, and the cementitious material is used in the fields of mine cementing filling and building materials. The four-element system cementitious material includes the following raw materials in percentage by mass: 20-60% of water-quenched blast furnace slag, 10-40% of waste incineration bottom ash, 20% of pretreated waste incineration fly ash and the balance of desulfurization gypsum. The low-cost four-element system cementitious material is used to replace cement to prepare mine cementing filling materials, and is also used to prepare concrete materials for construction industry.