Sr2MgSi2O7: Eu2+, Dy3+ was chosen for the investigation about the effect of grain surface on the long afterglow properties. Three pulverizing ways (manual grinding, ball milling and roller milling) were carried out to obtain different grain surface morphologies of particles. The most grains of the luminous powders obtained by roller milling are intact, while those obtained by ball milling are tattered with the grains surface destroyed. As for manual grinding, part of the grains surface are destroyed. The initial luminescent intensity of the phosphor pulverized by roller milling is nearly twice of that prepared by ball milling. After ball milling, the pulverized phosphor is sintered once again at 1000 degrees C in reducing atmosphere. It follows that the luminescence properties are enhanced significantly with the opposite variation trend compared with that prepared by roller milling. This is closely related to the change of defect density on the grain surface of these phosphors. (C) 2015 Elsevier Ltd. All rights reserved.