The invention provides a technological method for asymmetrically replacing a semi-chord of a main chord of a spud leg. The technological method is used for replacing a subsection with defects on one of the semi-chords and comprises the following steps: cutting, replacing, welding and reverse deformation; in the cutting step, utilizing a cutting tool to cut off the subsection with defects of the semi-chord to form a window; in the replacing step, placing the new subsection of the semi-chord at the window and utilizing a tool to clamp the new subsection on the main chord; in the welding step, welding the new subsection of the semi-chord on the main chord; and in the reverse deformation step, carrying out reverse deformation before and/or after the replacing step and during the welding step to offset or compensate the bending deformation, deviating from the central shaft, of the main chord during the cutting and welding steps. The technological method is adopted to carry out cutting, welding and replacing on the single side, so that welding quality and postwelding precision tolerance requirement can be effectively ensured, the replacing method of a conventional new main chord is broken through and the construction cost is greatly reduced.