Using a long chain cashew nut shell oil of fifteen carbons,the waterborne alkyd resin was synthesized by salt forming method,and the waterborne alkyd resin was used as the base material to prepare the waterborne alkyd paint.The flexibility of the product can easily reach level 1.Even in the case of thick coating,the bending strength can reach 1 mm,and the impact strength can reach 80~100 cm.The salt fog resistance,damp heat resistance and water resistance time can be increased by more than 25%~30%on average,and the drying speed,especially the solid drying speed,can also be shortened to 15~16 hours,the comprehensive performance was significantly improved.