The invention provides an offshore wind power duct rack grouting material which comprises a dry material and water, wherein the dry material comprises the following components in percentage by mass: 25.0-40.0 percent of Portland cement, 1.0-5.0 percent of sulphoaluminate cement, 45.0-55.0 percent of quartz sand and 5.0-15.0 percent of admixture; the addition amount of the water is proper. The invention further provides a construction method of the offshore wind power duct rack grouting material. According to the offshore wind power duct rack grouting material and the construction method thereof, the material has the characteristics of high liquidity, high pumpability, super-high early-strength, ultrahigh strength, high durability, good water dispersion resistance, zero shrinkage and high fatigue resistance, can be conveyed by a rubber pipeline by adopting a pumping and grouting construction mode, is suitable for underwater grouting and is also suitable for grouting connection between the offshore wind power duct rack and steel pipe pile foundation.