The invention belongs to the technical field of hot-galvanizing high-strength steel for automobiles and particularly relates to 600MPa-level vanadium-containing hot-galvanizing dual-phase steel and a preparation method thereof. The dual-phase steel comprises the following components in percentage by weight: 0.04%-0.10% of C, 0.10%-0.60% of Si, 1.30%-1.90% of Mn, 0.10%-0.50% of Cr, 0.05%-0.25% of Mo, 0.01%-0.06% of Al, 0.01%-0.05% of V, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.006% of N and the balance of Fe and inevitable impurities. According to the dual-phase steel, partial Cr and Mo are replaced with trace V and Si, so that the strength and hardenability of the dual-phase steel are improved, and meanwhile, the production cost is lowered; and by combining with a pre-oxidization reduction process, the surface galvanizing quality of the dual-phase steel is improved. The hot-galvanizing dual-phase steel prepared by virtue of the preparation method has excellent forming property, welding property and galvanizing property, oblivious cost advantage and remarkable economic and social benefits.