Na2SrMg(PO4)2: Ce3+, Mn2+ phosphor was prepared by high temperature solid state reaction. Its luminescence properties and energy transfer from Ce3+ to Mn2+ were investigated. The emission bands of Ce3+ and Mn2+peaking at 334 nm and 617 nm were attributed to 5d→4f transition of Ce3+ and 4T1(4G)→6A1(6S) transition of Mn2+, respectively. Dependence of Ce3+ and Mn2+ luminescence properties on their concentrations was investigated as well. With the increase of Mn2+ content, the emission intensity of Ce3+ could be observed to decrease, however, the emission intensity of Mn2+ was found to increase. It is indicated that the luminescence of Mn2+ could be sensitized by energy transfer from Ce3+ to Mn2+ in Na2SrMg(PO4)2 host. According to the Dexter's energy transfer formula of multipolar interaction, it is demonstrated that the energy transfer between Ce3+ and Mn2+ is due to the electric dipole-quadripole interaction of the resonance transfer.