The invention provides a halogen-free and thermal resistant composition, including a mixture of bismaleimide and maleimide with molar ratio of 99:1-50:50; a barbituric acid, wherein the molar ratio of the mixture and the barbituric acid is 93:7-80:20; and an epoxy resin, wherein (the mixture with the barbituric acid) and the epoxy resin have a weight ratio of 5:95 to 50:50. The mixture undergoes reaction at 110-130° C. for about 2˜7 hours to form a maleimide modified epoxy resin. The procedure of forming the composition is solvent-free, thereby providing improved integrity for electronic packaging, lower curing temperature, and a simplified process.