The invention relates to a preparation method of a polylactic-acid hollow fiber dialysis membrane, which aims to overcome the defects that the conventional dialysis membrane material is poor in biocompatibility and easy to cause environmental pollution. The preparation method comprises the following steps of: adding polylactic acid, a pore-forming agent, a toughening agent and an inorganic filler to a solvent, stirring the components at 40-120 DEG C for 8-12 hours to obtain a spinning solution, and then deforming the spinning solution; carrying out extrusion moulding on the defoamed spinning solution and core liquid which respectively pass through an external channel and an inner channel of a spinning nozzle, thus obtaining nascent fibers; curing the nascent fibers in coagulating bath after the nascent fibers pass through air gaps of 0 to 50cm, thus forming a nascent polylactic-acid hollow fiber membrane; collecting the nascent polylactic-acid hollow fiber membrane by a coiler at a speed of 1-30 m / min, thus obtaining the polylactic-acid hollow fiber membrane; and finally soaking the membrane in circulating deionized water at 20-45 DEG C for 6 to 48 hours, and taking out and drying the membrane. The preparation method has the advantages of little pollution and energy conservation; and the prepared dialysis membrane is good in biocompatibility and low in adsorption capacity of proteins, has a good elimination effect on urotoxy matters, and is biodegradable.