The invention relates to composite aqueous passivation solution and a preparation method thereof for hot galvanizing surface treatment. The passivation solution comprises the following components in percentage by weight: 0.1%-0.2% of fluorine titanate, 0.1%-0.2% of fluorine zirconate, 0.2%-0.4% of phosphate radical-contained matter, 0.01%-0.05% of soluble fluoride, 2%-3% of silicane A, 2%-3% of silicane B, 0.01%-0.05% of glacial acetic acid and the balance of water and soluble alkali. The preparation method comprises the following steps of: sequentially adding silicane A, glacial acetic acid and silicane B to water and uniformly stirring; then sequentially adding fluorine titanate, fluorine zirconate, soluble fluoride and phosphate radical-contained matter; and finally adding alkali. In the method, the passivation solution is prepared from hydrolysis type silicane, no chromate is contained in raw materials, no alcohol matter is added in the preparation process, and therefore, the preparation method reduces environmental pollution and meets the requirements of WEES & ROHS instructions; and the passivation solution has the advantages of short passiavation and drying time and energy saving and is suitable for continuous production, and the passivation film formed from the passivation solution has excellent corrosion resistance.