The invention provides a low-temperature early-strength high-strength underwater grouting material. The low-temperature early-strength high-strength underwater grouting material consists of the following ingredients in parts by weight: 30-45 parts of ordinary Portland cement, 45-60 parts of fine aggregate, 5-10 parts of mineral powder, 2-4 parts of encryption silica fume, 0.5-1 part of a compound expanding agent, 0.2-0.5 part of an early-strength powdery water reducer, 0.1-0.5 part of nano hydrated calcium silicate, 0.3-0.5 part of a compound early-strength agent and 0.1-0.3 part of a dispersion-resistant compound. The low-temperature early-strength, low-temperature high-strength and dispersion resistant properties of the low-temperature early-strength high-strength underwater grouting material in water are improved at the same time in the four aspects of reducing the void ratio of the aggregate, optimizing the expanding components and improving the nano early strength and the dispersion resistance, the construction performance, such as the water holding performance and the viscosity, of the grouting material are remarkably improved, the 1d strength and the 28d strength of the grouting material under the undersea low-temperature condition are effectively improved, and the underwater dispersion resistance of the grouting material can be greatly improved. The low-temperature early-strength high-strength underwater grouting material has favorable low-temperature early-strength, low-temperature high-strength and underwater dispersion resistant functions.