Abstract The preparation conditions of phosphor based on Ba2Mg(BO3)2 host was systematically investigated, the effect of reduction atmosphere on the Ba2Mg(BO3)2:Eu2+/3+ phosphor was investigated in detail as well. Eu2+ and Eu3+ ions coexist in the host lattice on condition of CO reduction atmosphere, which results in multiple luminescence centers, therefore the phosphor could be selectively excited by 365 nm, 395 nm UV. The yellow emission intensity at 564 nm was remarkably enhanced when more Eu3+ ions were reduced to Eu2+ ions in atmosphere of H2, but Eu3+ ions were not totally reduced yet. By means of the control of reduction condition, high brightness yellow phosphor Ba2Mg(BO3)2:Eu2+/3+ was prepared accordingly. Color coordinate of yellow phosphor is very close to white light area, this phosphor could be excited by near ultraviolet (UV) InGaN chip, combing with blue light, and applied in white light-emitting diodes (WLEDs).