The invention discloses an epoxy resin composition with high bio-based content, which comprises: 100 parts of epoxy vegetable oil, 1-100 parts of unsaturated bio-based dicarboxylic acid, and 1-10 parts of curing accelerator in terms of mass parts of raw materials part; 1-10 parts of free radical initiator; curing accelerator 1 is tetrabutylammonium bromide, triphenylphosphine, 2-methylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol Or boron trifluoride, the free radical initiator is a peroxide or azo curing agent. The invention also discloses its curing method and application. The epoxy resin composition with high bio-based content of the present invention greatly improves the mechanical properties of the material. The main raw materials are all from bio-based renewable resources, and they are all green and non-toxic substances. They have the potential to alleviate the oil crisis and reduce carbon dioxide emissions. A certain positive effect, while reducing the damage to the human body, also reduces the pollution to the environment, which is beneficial to industrial applications, especially the application in coatings.