Abstract: Novel bule emitting phosphors Sr_2MgSi_3O_9∶Eu~(2+) was synthesized by gel-combustion method in weak reductive environment.The phase structure, microstructure and luminescent properties of the as-synthesized phosphors were investigated by XRD, SEM and fluorescence spectrophotometer. The results showed that Sr_2MgSi_3O_9∶Eu~(2+) phosphors possess the similar tetragonal crystal structure as that of Sr_2MgSi_2O_7 . The initial particles of the phosphors are nearly spherical in shape, and the grain size is about 100 nm in diameter. The excitation spectrum of Sr_2MgSi_3O_9∶Eu~(2+) is a broad band in the range of 250-450 nm,the main peak is at 424 nm and the secondary peak is at 400 nm, which can be excited efficiently by UVLED chip whose emission peak locates at 360-400 nm. The emission spectrum is also a broad band, the emission peak is at about 470 nm. It's ascribed to Eu~(2+) typical transition from 4f 5d to 4f.Sr_2MgSi_3O_9∶Eu~(2+) shows good prospect for blue phosphors of white LED.