A preparation of Tb surface modified hydroxylapatite fluorescent nano particle, which uses cetyl trimethyl ammonium bromide as additive, adds calcium salt solution into mixed solution of phosphate radical and cetyl trimethyl ammonium bromide drop by drop, adds aqueous ammonia drop by drop to regulate pH value of the solution, precipitates hydroxylapatite particles from the solution to form suspending liquid of hydroxylapatite, regulates pH value with alcaine, adds Tb³⁺ drop by drop into suspending liquid to substitute surface portion Ca²⁺ of hydroxylapatite nano particlewith Tb³⁺, obtains rice shaped particles by filtering, abstersion, vacuum drying and collecting, which has a long diameter of 40-60mm, and short diameter of 15-20 mm. The inventive preparation is simple in process, easy to get raw materials. The product is characterized by evident fluorescent feature, miniature, good biodegradability, which can be used as stable biological probe material.