A method for preparing a negative electrode active material, a negative electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a negative electrode active material including the steps of (a) preparing a coating composition including a precursor of metal-phosphorus-oxynitride; (b) forming a precursor layer on a negative electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorus-oxynitride protective layer on the negative electrode active material by heat treating the negative electrode active material having the precursor layer formed thereon. The method for preparing a negative electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.