The invention discloses a dry-mixed ground mortar which comprises the following raw materials by mass percent: 10-20% of cement, 8-15% of mineral slag powder, 3-8% of steel slag powder, 1-3% of desulfurization gypsum, 60-70% of steel slag sand, 1-3% of emulsion powder, 0.1-0.3% of water reducing agent and 0.1-0.3% of water-retaining agent. According to the invention, solid waste-steel slag powder is utilized to prepare the steel slag sand for replacing natural sand and the mineral slag powder, steel slag micro-powder and desulfurization gypsum are used as binding materials for replacing some cement, so as to prepare the dry-mixed ground mortar. The dry-mixed ground mortar prepared according to the invention is capable of reducing the production cost and is beneficial to resource utilization, energy saving and environmental protection; the dry-mixed ground mortar prepared according to the invention is a dry powdered ground mortar which is suitable for long-term storage and convenient in transportation; the mortar has the characteristics of high peaceability, excellent water-retaining property, no sand falling, no shrinkage or bulge, smooth surface, and the like.