A novel method of second harmonic generation (SHG) is reported. A permanent second order nonliearity which is zero in theory has been induced simultaneously by ultraviolet (UV)-excited poling in a high concentration Er-Yb co-doped fiber Bragg gratings, and the phase-match has been satisfied with periodic structure. When a 980-nm laser diode (LD) pumped the fiber gratings, SHGs in such a fiber gratings with low pump power (<4 mW) were abserved and the intensity increased with the increase of pump power. The SHG light radiating phenomenon was observed under microscope and some microscope photograph were taken. It was found that the radiation occurred only in the core of the fiber gratings. And then UV radiation from the structure was also recorded.