The invention relates to a two-component polyurethane resin for metal packaging tanks, and a preparation method thereof. The host of the two-component polyurethane resin comprises, by mass, 25-50% of polyester polyol, 5-15% of epoxy resin, 0.2-1.0% of a coupling agent and 35-65% of a solvent; a curing agent is polyisocyanate, and the host is mixed with the curing agent according to a mass ratio of 100:5-20; and the hydroxy group of the host reacts with isocyanate in the curing agent to generate polyurethane. The polyester polyol is prepared through ester interchange of dimetyl terephthalate, dicarboxylic acid, acid anhydride, dihydric alcohol and polyol, esterification and a condensation polymerization reaction, or is prepared through esterification of the dicarboxylic acid, the acid anhydride, the dihydric alcohol and the polyol, and the condensation polymerization reaction. The preparation method has the advantages of easily available raw materials, simplicity and reliability. The two-component polyurethane resin can be well bonded with a metal substrate and a film, has good deep punching, corrosion and boiling resistance, and can be widely used in the metallic tank industry.