The invention discloses a halogen-free epoxy adhesive which is prepared from the following components in parts by weight: 10-80 parts of phosphorus-containing epoxy resin, 10-40 parts of rubber modified epoxy resin, 10-50 parts of a toughening agent, 1-25 parts of a curing agent, 0.01-1.0 part of a curing accelerant, 0-80 parts of inorganic filler, 1-40 parts of a phosphorus-containing fire retardant, 1-40 parts of a nitrogenous fire retardant and 0.01-1.0% of an antioxidant. According to the invention, the components are dispersed into an organic solvent according to the proportion, so that the adhesive with the solid content of 30-50wt% can be obtained. The halogen-free epoxy adhesive does not contain halogen, and uses the phosphorus-containing fire retardant and the nitrogenous fire retardant to cooperate with a flame-retardant adhesive system, thus reducing the dosage of the phosphorus-containing fire retardant, and overcoming the negative effect caused by using a great deal of phosphorus-containing fire retardant; the halogen-free epoxy adhesive is good in fire resistance, excellent in heat resistance, high in reliability and better in mechanical property. The invention also discloses a cover film prepared from the halogen-free epoxy adhesive, and the cover film has the fire resistance of UL 94V-0 level, excellent stripping strength, heat resistance and processing performance.