A method for converting a carbon source into ethylene glycol includes: providing a plasmid, in which the plasmid includes gene sequences of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6; implanting the plasmid into cyanobacteria through an electroporation treatment, so that modified cyanobacteria are obtained; and providing the carbon source to the modified cyanobacteria, so that the modified cyanobacteria convert the carbon source into the ethylene glycol.