The present invention discloses a mehtod for repairing top of storage tank, including the procedures of survey, preparing material, safety measure and removing rust, also possessing the technologicalsteps of (A) constructing internal surface layer; (B) constructing intermediate layer; (C) construcing external surface layer; (D) making age-inhibiting layer; and (E) forming and curing to make glass fibre reinforced plastic composite tank top. Said invented method is simple and quick in construction, reasonable in structure, short in construction period, low in cost and safe and reliable in use.