Disclosed is a method for extending a shelf life of vinyl ester resin or unsaturated polyester resin during transportation or general storage. The method includes the step of enhancing an oxygen content of the vinyl ester resin or the unsaturated polyester resin, such that the self-polymerization reaction of reactive functional groups having carbon-carbon unsaturated double bonds of the vinyl ester resin or the unsaturated polyester resin can be minimized, so as to slow down occurrence of a gelation phenomenon of the vinyl ester resin or the unsaturated polyester resin in a long-time transportation or storage, and further to decrease a monetary loss.