The invention relates to functional norbornenes as initiators for radical polymerization, its polymer and fabrication method thereof. More particularly, the functional norbornenes can be selectively polymerized by ring-opening metathesis polymerization or radical polymerization to obtain various polynorbornene derivatives or grafted copolymer materials. The polynorbornene derivatives and grafted copolymer materials not only exhibit excellent functional properties but also enhanced physical and chemical properties after modification. The polynorbornene derivatives and grafted copolymer materials disclosed in the invention exhibit excellent heat resistance, transparency and water resistance. The invention also deals with a process for producing such derivatives and materials having controllable molecular weight with narrow molecular weight distribution.