The invention discloses a formula of a submerged plant planting mud ball matrix and a preparation method. The method comprises the steps of 1, preparing raw materials including common loess which is common planting high-quality soil with no root systems in soil or gravel or grit or other large particles, sodium polyacrylate of which the MW is 106-107, and activated carbon powder which is soaked with a rooting solution and a nutrient solution, wherein the particle size is 500 meshes; 2, mixing the raw materials, wherein common loess, silicate cement, sodium polyacrylate and activated carbon powder are mixed to be uniform according to the preset proportion, water is added into the uniformly-mixed matrix step by step and stirred to be uniform till molding is achieved; 3, performing mud ball seed wrapping. According to the matrix prepared in the mode, the effect of supporting the submerged plant root system is achieved, no obvious inhibition effect is caused for plant growth, the certain nutrient effect can be provided for submerged plant root system growth, and the matrix is applicable to seed throwing planting in the large water surface with the large water depth and certain waves.