The invention relates to a construction method for building a large-scale offshore wind farm with depth more than 2m, which mainly comprises the following steps: dragging a construction ship to the set position by a shoal water tug boat, starting a lifting device on the construction ship after the construction ship is positioned to lift the ship body from the water level by 2-3 m; dragging a vehicle pontoon provided with devices such as a steel pipe pile, a blower operating platform, a tower cylinder, a blower bin, a hub, blades and the like near the construction ship through the shoal water tug boat and then anchoring and positioning; and then constructing by utilizing devices such as a 400-t fully-revolving crane and the like on the construction ship. The invention leads the construction ship to perform the construction on the large-scale offshore wind farm with depth equal to or more than 2m because operation, loading and dragging are separated, has the advantages of continuous operation without being influenced by tide, convenient construction, high speed, high efficiency, low construction cost, and the like, and fills up the blank of constructing and building the large-scale offshore wind farm at the zone of 2-5 m in the world.