The invention discloses a mine dump horizontal flat plate remediation and ecological restoration method. The method comprises the following steps of: comprehensively optimizing and determining the slope grade, the slope length and the flat plate width of a dump according to experience, calculation and land use properties, wherein the design slope cutting open grade of the accumulation slope of the dump comprises three grades, the slope height of each grade is 9 to 11 m, the slope flat plate width is 4 to 8 m, the slope ratio of the first grade is 1:(1.9-2.1), the slope ratio of the second grade is 1:(1.7-1.8), and the slope ratio of the third grade is 1:(1.4-1.60); remediating the flat plate into level; planting grass on the first grade slope and the second grade slope by using a grout-built stone arch frame; performing design construction on a slope bottom apron, a grout built rubble slope flat plate and a drainage ditch and a slope trim of the flat plate; performing a vetiver grass slope protection greening technology on the third grade slope; and sowing bahia grass on the flat plate of the dump to cover the flat plate and conserve water and soil in a short term by utilizing the fast-growing and poor-resistant properties of the bahia grass first and then planting fruit trees or crops on the flat plate. In the method, engineering measures and biological measures are taken comprehensively to ensure the safety of a mine dump and achieve a good ecological restoration effect and a good landscape effect; moreover, plants suited to local conditions are planted and the construction cost is low.