The invention discloses a construction method of an offshore wind power jacket. The construction method comprises the following steps: a first component and a second component are made to lean againsta first template piece to be positioned, a first connecting piece is fixed between the first component and the second component, and a top frame is formed; a third component and a fourth component are made to lean against a second template piece to be positioned, a second connecting piece is fixed between the third component and the fourth component, and a bottom frame is formed; and the top frame is moved to the upper part of the bottom frame, and the top frame is fixed to the bottom frame to be assembled into the jacket. The top frame and the bottom frame are vertical, the manufacturing precision of the top frame and the bottom frame is ensured, the top frame and the bottom frame can be manufactured independently and separately, the production efficiency is improved greatly, the top frame can be directly moved to the upper part of the bottom frame to be fixed, turning over for erecting is not needed, the engineering quantity of aloft work is decreased, and safety is high.