A series of emission-tunable Ca9Y(PO4)(7):Eu2+, Mn2+ nanophosphors were synthesized by the hydrothermal method. X-ray diffraction (XRD), photoluminescence (PL), Rietveld refinement and transmission electron microscopy (TEM) were used to characterize the samples. The results showed that the pH value played a key role in determining the morphology of nanophosphors. With the increase of pH values in the initial solution, the morphologies of samples changed from rod-shapes to ball-shapes. And the decrease of aspect ratios accompanies a change in luminescence properties. The energy transfer from Eu2+ to Mn2+ in Ca9Y(PO4)(7) was achieved due to the electric multipolar interaction of the electric dipole-quadrupole mechanism, and the critical distance (R-c) between them was calculated by the concentration quenching method.