The invention discloses a sealing anchor bolt for mounting an anchor bolt cage of a maritime wind unit and a construction method thereof. The sealing anchor bolt comprises an upper anchor plate tension end, a lower anchor plate fixed end and a anchor bolt body, wherein the anchor bolt body comprises a plurality of groups and by adopting the same structure and distributed uniformly in a circumferential array, the anchor plate body is connected between the upper anchor plate tension end and the lower anchor plate fixed end; the lower anchor plate fixed end is casted at the bottom of the first period concrete; the top of the first period concrete is casted with the second period concrete, the upper anchor plate tension end is supported at the top of the second period concrete. During the construction and operational use period, because of the expansion and tension effect caused by axial force of the pre-stressed anchor bolt body, the distance between the upper and lower anchor plates canbe increased, which makes gap appeared between the upper and lower anchor plates. Then the sealing state can not be kept, leading to direct exposure of the anti-corrosion coating layer in the gap to the concrete layer, thus the coating is easy to be damaged and anti-corrosion ability may be lost. The above problem can be solved by the sealing anchor bolt and construction method thereof for mounting anchor bolt cage of maritime wind unit