The present invention relates to a method for producing carbon-coated lithium iron phosphate nanopowder and the lithium iron phosphate nanopowder produced according to the method, the method comprising the steps of:(a) producing a mixed solution by putting a lithium precursor, an iron precursor, and a phosphate precursor into a reactant solvent; (b) producing amorphous lithium iron phosphate nanoseeds by putting the mixed solution into a reactor and causing a reaction; and (c) producing lithium iron phosphate nanopowder partially or wholly coated with carbon on a particle surface by thermally treating the produced lithium iron phosphate nanoseeds. Thus, through a simple process with two steps, it is possible to produce, in a short time, the lithium iron phosphate nanopowder of which a particle size and particle size distribution are controlled and which has a carbon coating layer formed on particles. Furthermore, a lithium secondary battery which includes the produced carbon-coated lithium iron phosphate nanopowder as a cathode active material can be excellent in terms of capacity and stability.