The invention discloses a porous long-lasting phosphor material. The chemical formula of the porous long-lasting phosphor material is M2-x-y MgSi2O7: xEu<2+>, yDy<3+>, the material is prepared from MCO3, SiO2, MgO, Eu2O3 and Dy2O3 by using a high-temperature solid-phase method, M is one of Sr, Ca or Ba, x is greater than or equal to 0.01 or less than or equal to 0.06, and y is greater than or equal to 0.01 or less than or equal to 0.1. The invention further discloses a preparation method of the porous long-lasting phosphor material. The preparation method comprises the following steps: weighing MCO3, SiO2, MgO, Eu2O3 and Dy2O3 according to components of the chemical formula, grinding, pre-burning, adding a pore forming material, tabletting, sintering, and cooling, thereby obtaining the porous long-lasting phosphor material. The porous long-lasting phosphor material is high in surface light absorption amount, moderate in defect density in crystal granule and high in light emission property; by adopting the preparation method, the surface light absorption amount and the defect density of the crystal granules are increased, good operability can be achieved, and a simple synthesis process is available.