The object of the present invention is to provide polyester resin for engineering machinery, the polyester resin comprises polyhydric alcohol, aromatic polybasic acid, a branching agent, an acidolysisagent, an esterification catalyst, an antioxidant and a curing accelerator, the acidolysis agent comprises one or a mixture of at least two of isophthalic acid (IPA), adipic acid (ADA), 1,4-cyclohexanedicarboxylic acid (CHDA), fumaric acid (FCC), trimellitic anhydride (TMA), succinic acid (BA) and dodecanedioic acid (DDDA), more preferably comprises at least the IPA and the ADA; the polyester resin can be combined with curing agents (TGIC, hydroxyalkylamide or blocked isocyanate), curing accelerators, pigments, fillers, leveling agent, degassing agents and the like to prepare powder coatingsfor engineering machinery. Compared with conventional polyester resin, the polyester resin has excellent mechanical properties and flexibility, water boiling resistance, weather resistance, low temperature frost resistance, thick coating resistance and unchanged performance when the curing temperature is changed, and crack resistance under freezing impact and bending of iron plates and electrophoresis plates at-18 DEG C, and the polyester resin is very suitable for coating in the field of engineering machinery.