NOVELTY - Polyethylene glycol and potassium permanganate is added to purified water, reaction kettle is added in oven, heated, cooled and centrifuged, to obtain manganese oxide nanowire. The obtained manganese oxide nanowire is provided into tube furnace and cooled, to obtain porous manganese oxide nanowire. The obtained porous manganese oxide nanowire is provided into tube furnace and heated. The product is provided into mixed gas of acetylene and argon gas or nitrogen, and cooled to room temperature, to obtain carbon-coated manganese oxide coaxial wire.    USE - Preparation of carbon-coated manganese oxide coaxial wire used for lithium ion battery.    ADVANTAGE - The carbon-coated manganese oxide coaxial wire is efficiently prepared with improved energy density and power density, and high specific capacity, by simple method.    DETAILED DESCRIPTION - Polyethylene glycol (1-3 mL) and potassium permanganate (0.1-0.2 g) is added to purified water (30-50 mL), reaction kettle (60-100 mL) is added in the oven, heated at 160-180 degrees C for 5-15 hours, naturally cooled to room temperature, and centrifuged at 60-80 degrees C, to obtain manganese oxide nanowire. The obtained manganese oxide nanowire is provided into a tube furnace under air atmosphere, heated at speed of 1-5 degrees C/minute, temperature is increased at 550-650 degrees C for 3-10 hours and naturally cooled, to room temperature, to obtain porous manganese oxide nanowire. The obtained porous manganese oxide nanowire is provided into the tube furnace at speed of 40-80 mL/minute into an inert atmosphere for 30-60 minutes, air discharge is cleaned in the furnace, and then heated at rate of 5-10 degrees C/minute, and heated at 500-600 degrees C for 30-60 minutes. The product is provided into mixed gas of acetylene and argon gas or nitrogen. The volume ratio of acetylene and argon gas or nitrogen is controlled to 1:5-10, time is controlled for 40-80 minutes and naturally cooled to room temperature, to obtain carbon-coated manganese oxide coaxial wire.