A modified bismaleimide resin is made by modify bismaleimide with aromatic diamine that contains fluoro substituents through chain-growth polymerization; and modified bismaleimide resin is excellent in physical properties including a low dielectric constant Dk (3 GHz) less than 3.0, a dissipation factors (3 GHz) less than 0.02, a low resin water absorptivity ranging from 0.21% to 0.33% and an excellent processability, and is particularly suited for producing a copper clad laminate that is required to have dielectric constant Dk (3 GHz) less than 3.