This invention relates to a method for preparing rare earth Eu-activated calcium sulfide or alkaline earth metal sulfide red-fluorescent material. The method comprises: (1) weighing calcium carbonate or alkaline earth metal carbonate, europium oxide and sulfur according to the chemical formula of Ca1-xSn : Eux or MyCa1-x-ySn : Eux (x = 0.001-0.04 mol, n = 1-3, M = one or more of Mg, Sr, Ba and Zn, and y = 0-1); (2) grinding and mixing the raw materials completely, and placing in a torrefaction container; (3) torrefying at 900-1200 deg.C for 30-120 min to obtain red-fluorescent powder. The method has such advantages as simple operation, low cost and no harm to operators. The emitting peak of the fluorescent material can change within the range of 50 nm, thus is suitable for different circumstances. |