Abstract: In order to improve the toughness of shellac(SHL) resin, eleostearic acid(EA) was added to shellac resin through Diels-Alder reaction to prepare toughened shellac(TS) resin, and its structure was analyzed by gel chromatography(GPC), infrared spectroscopy(FT-IR) and ¹³C nuclear magnetic resonance(¹³C NMR). And then, tannic acid(TA) was added to prepare SHL-TA, and TS-TA composite coating. The effects of TA and EA on the anti-corrosion properties of shellac resin coating were analyzed by electrochemical workstation, neutral salt water resistance and neutral salt spray(NSS) resistance tests. The results showed that the TS modified by EA through the Diels-Alder reaction exhibited good toughness. When the weight ratio of SHL and EA was 1.8:1, the elongation at break of TS-3 coating was as high as 381.81%. In addition, the hydrophobicity of shellac coating was increased by the modification of EA, and its static water contact angle reached 95.01°.The addition of TA could improve the adhesion of the coating on the metal substrate, and the combined action of TA and EA could enhance the anti-corrosion of SHL coating. The best corrosion protection system was TS-3-TA coating. After immersion in 3.5% NaCl for 48 h, the polarization resistance of the coating was still 36.3 kΩ, far more higher than that of other coatings. And the time of neutral salt water resistance and neutral salt spray(NSS) resistance tests of TS-3-TA, which was prepared in alkali system, was 120 h and 168 h.