The invention discloses a magnesium phosphate cement foamed concrete sand stabilizing plate and a preparation method thereof. A magnesium phosphate cement base material is prepared from soluble phosphate, retarded adhesive material, magnesium oxide, fine sand, water and inorganic foaming agent or foam prepared by plant foaming agent. A preparation method of the magnesium phosphate cement foamed concrete sand stabilizing plate is prepared by preparing soluble phosphate, retarded adhesive material, magnesium oxide, fine sand at ratio, fully mixing the components, adding water to mix evenly; filling the foam prepared by the animal plant foaming agent or inorganic foaming agent, and stirring evenly; placing to a plate-shaped module and maintaining; after the slurry is completely set, demoulding and preparing the magnesium phosphate cement foamed concrete sand stabilizing plate. The magnesium phosphate cement foamed concrete sand stabilizing plate is low in material cost, green and environment-friendly, stable in physical performance, strong in weather-proof ability, simple in construction and installation, and wide in application prospect in desertification control project.