A series of blue-emitting phosphors M2B5O9Cl: Eu2+(M=Ca, Sr) were synthesized by solid-state methods. And the phosphors were characterized by XRD and photoluminescence emission (PL) and excitation (PLE) spectra. The factors that affect the PL intensity of phosphor Sr2B5O9Cl have been investigated, and the optimal conditions to obtain the blue emitting phosphor are 8 mol% Eu2+concentration, 5.0mol % excess of SrCl2. As Ca partially or completely substituted Sr in the host Sr2B5O9Cl, the emission peak shifts from 425 to 453 nm. The most important is that the phosphors M2B5O9Cl: Eu2+(M=Ca, Sr) show strong absorption in the region of 350—400 nm, which matches well with the emission of the near-ultraviolet or purple LED chips. Comparison with the commercial blue-emitting phosphor, the PL intensity of phosphor Sr1.92Eu0.08B5O9Cl is about 1.8 times that of the commercial blue emitting phosphor BAM. Thus, the phosphors M2B5O9Cl: Eu2+ (M=Ca, Sr) show great potential as the candidate for blue phosphor in n-UV or purple based white LEDs.