[Objective] The changes in plant growth, soil moisture content, and slope erosion on the slope of a dump field formed by the development of grassland mineral resources under different regulated deficit irrigation treatments were determined in order to provide a scientific basis for the implementation of restoration irrigation technology. [Methods] Five regulated deficit irrigation treatments were set up, and full irrigation was used as the control. The rank sum ratio method was used to determine the best water replenishment scheme for artificial grassland on abandoned land slopes. [Results] As water deficit increased, the growth and development of plants of an artificial grassland on abandoned slopes of a grassland mining area were restricted. The above-ground biomass and community coverage of plants decreased significantly (p＜0.05). In the early stage of plant growth, the sediment yield and runoff on the slope increased significantly with increasing irrigation amount (p＜0.05). There were no obvious changes in sediment yield and flow rate between treatments. Compared with the regulated deficit irrigation treatments, the water use efficiency of mild and moderate regulated deficit irrigation (when the soil moisture content reached 55% and 45%, respectively, of the soil field water holding capacity) was relatively high. [Conclusion] A comprehensive evaluation of the effects of artificial grassland construction on water storage, soil conservation capacity, and irrigation water use efficiency showed that mild deficit-regulated irrigation (soil moisture content reached 55% of soil field water holding capacity) produced similar effects on water use efficiency and artificial grassland construction benefits. The combination was good, and the effect on soil erosion prevention and control was obvious. This level of regulated deficit irrigation could be used as the preferred choice for constructing artificial grasslands in the mine wasteland of the study area.