The invention discloses a method for preparing a polylactic acid-amorphous calcium phosphate nano composite fiber material, which comprises the following steps of: preparing aqueous solution A and aqueous solution B by using water-soluble calcium salt, water-soluble phosphate and polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (P123) as raw materials, and then performing precipitation reaction under the alkali condition to obtain amorphous calcium phosphate nano granules; and then dispersing the amorphous calcium phosphate nano granules into mixed solution of nitrogen-nitrogen-dimethyl formamide and tetrahydrofuran, adding polylactic acid, stirring till full dissolution, and performing electrostatic spinning to obtain the material. The preparation method has the advantages of simple process, quickness, low cost and the like, and is suitable for large-scale production. The prepared polylactic acid-amorphous calcium phosphate nano composite fiber material has good biocompatibility, high specific surface and internal through porous structure; and the composite material can be widely applied in the field of biomedical engineering.