The invention discloses spherical nano-porous hydroxylapatite prepared through shells and a preparation method thereof, and belongs to the technical field of material preparation. According to the hydroxylapatite prepared through the method, the hydroxylapatite is in a spherical shape, the diameter is 4-5 micrometers, the dispersity is good, the specific surface area is 270 cm<2>/g, the average pore diameter is 18 nm, carbonate radicals are contained, the components are similar to those of hydroxylapatite in the bones, and the biocompatibility is good. The preparation method comprises the following steps that the shells are washed, dried and ground, acetic acid with the concentration of 0.1 g/mL is added to fully react with the ground shells, an H3PO4 solution is dropwise added into a prepared calcium acetate solution, trisodium citrate is added, urea is added after reacting under stirring are performed, a prepared solution is stirred to be subjected to a reaction for 5 min in a water bath at the temperature of 80 DEG C-90 DEG C, standing is performed until precipitates occur, and the obtained precipitates are filtered, washed, dried and then collected. According to the method, shell powder does not need to be calcined, the reaction time is short, the pH does not need to be adjusted, operation is easy, the repeatability is good, the raw materials are easy to obtain, and not only is waste utilization achieved, but also energy conservation and emission reduction are facilitated.