Relating to the technical field of artificial stone, the invention discloses a preparation method of a self-cleaning outdoor artificial stone plate. The self-cleaning outdoor artificial stone plate isprefabricated from ultra-high performance mineral powder with a compressive strength of 100-150MPa. The ultra-high performance mineral powder comprises the following raw materials by weight: 80-100 parts of mineral active powder, 8-13 parts of titanium dioxide, 150-220 parts of self-cleaning aggregate, 4-8 parts of nano silicon dioxide, 0.5-2 parts of a water repellent, 10-15 parts of water, 2-4parts of a water reducing agent and 4-10 parts of a pigment. The artificial stone plate provided by the invention has the characteristics of good volume stability, good self-cleaning performance, lowshrinkage, no buckling deformation in use, extremely low water absorption rate, good durability, no aging or other problems, good surface stain resistance, and low overall comprehensive cost, and is suitable for application and popularization.