The invention relates to a single-pole attachment fabricated mooring structure for an offshore wind turbine foundation and a construction method. The single-pole attachment fabricated mooring structure is characterized by comprising a concrete bearing platform and a plurality of steel pipe piles of which the upper ends are obliquely inserted into the concrete bearing platform; the upper portion of the side wall of the concrete bearing platform is provided with a steel platform and a vertical steel ladder of which the upper portion is arranged in the steel platform in a penetrating mode; the concrete bearing platform and the side edges of the steel pipe piles are provided with a vertical berthing member; the berthing member comprises a plurality of horizontally-arranged mooring steel columns and a plurality of vertically-arranged berthing steel pipes, and the multiple horizontally-arranged mooring steel columns and the multiple vertically-arranged berthing steel pipes are connected with one another; the upper portion of the bearing member and connection steel pipes on the side surface of the concrete bearing platform are connected through flanges; and all subsections of the steel ladder are connected through flange bolts. According to the single-pole attachment fabricated mooring structure for the offshore wind turbine foundation and the construction method, safe and convenient ship mooring and operation and maintenance work in a wide-tidal-range sea area with heavy storm waves can be achieved, the mooring structure can be replaced and maintained conveniently, the adaptability of wind turbine foundation mooring to the severe sea condition is improved, the structural strength and stability of a wind turbine foundation mooring system are improved, and the mooring structure and the construction method have wide application prospects in ocean engineering.