The invention provides flame retardant engravable epoxy resin mortar. The mortar comprises a first composition mixture and a second composition mixture, wherein the first composition mixture comprises epoxy resin, a reactive diluent, a reactive toughening agent, a first filler, a flame retardant, hollow microspheres, a flame retardant, a thixotropic agent and pigments; the second composition mixture comprises a curing agent, a second filler, hollow microspheres, a thixotropic agent and pigments. The invention also provides a preparation method of the flame retardant engravable epoxy resin mortar comprising the above components. The preparation method comprises the following steps: preparing the first composition mixture, preparing the second composition mixture and mixing the first and second composition mixtures according to a specific proportion, thus obtaining the flame retardant engravable epoxy resin mortar.