Hot-dip aluminum-zinc coated steel sheet with excellent weatherability, corrosion resistance, and alkali resistance, and preparation method and surface treatment agent therefor

Disclosed are a hot-dip aluminum-zinc coated steel sheet with excellent weatherability, corrosion resistance, and alkali resistance, and an environmental-friendly surface treatment agent therefor. A surface-treated hot-dip aluminum-zinc coated steel sheet obtained by performing surface treatment on a hot-dip aluminum-zinc coated steel sheet with an environmental-friendly aqueous surface treatment agent that comprises components such as a matrix resin compounded by a specific solvent-free aliphatic aqueous polyurethane dispersion and an aqueous polyurethane-crylic copolymer, a silicone compound, a matrix resin curing agent, a water-soluble metal salt compound, and high-density polyethylene lubrication auxiliaries has excellent weatherability, corrosion resistance, and alkali resistance, and has desirable comprehensive performance such as machining formability.