NOVELTY - Modified carbon nanotubes and anhydrous toluene solution are ultrasonically-dispersed, to obtain liquid (A). Azobisisobutyronitrile and styrene are ultrasonically processing, to obtain liquid (B). Liquids (A) and (B) are reacted. Obtained polystyrene-modified carbon nanotube layer and 98% sulfuric acid are ultrasonically dispersed. Obtained sulfonated layer and deionized water are ultrasonically-dispersed, sodium citrate, hexamethylenetetramine and metal ion salt are reacted. Obtained precursor is calcined, to obtain carbon nanotube-based metal oxide nanosheet composite energy-storing material.    USE - Preparation of carbon nanotube-based metal oxide nanosheet composite energy-storing material (claimed).    ADVANTAGE - The method provides carbon nanotube-based metal oxide nanosheet composite energy-storing material having high specific surface area, conductivity, capacity and stability.    DETAILED DESCRIPTION - 0.4-40 mg Carbon nanotubes having hydroxyl group are weighed in flask, 60-5000 mL acetone is added, ultrasonically-dispersed for 5-25 minutes, 0.8-80 mg maleic anhydride is added, reacted at 25-30 degrees C for 10-12 hours, to obtain modified carbon nanotubes, and washed 4 times using acetone. 0.127-12.7 g Modified carbon nanotubes are taken, 30-3000 mL anhydrous toluene solution is added, and ultrasonically dispersed for 10 minutes, to obtain liquid (A). 80-8000 mg Azobisisobutyronitrile is added with 3.82-382 g styrene, and ultrasonically processed for 10 minutes, to obtain liquid (B). The liquid (A) and liquid (B) are mixed, reacted at 70-75 degrees C for 7-10 hours under nitrogen atmosphere, to obtain polystyrene-modified carbon nanotube layer, and washed 5 times using ethanol. 30-3000 mg Polystyrene-modified carbon nanotube layer is taken, added to 50-5000 mL 98% sulfuric acid, ultrasonically dispersed for 10 minutes, and stirred at 70 degrees C in reaction bath for 10-25 minutes, to obtain sulfonated polystyrene-modified carbon nanotube layer. 5-500 mg Sulfonated polystyrene-modified carbon nanotube layer is taken, added to 40-4000 mL deionized water, ultrasonically dispersed for 10 minutes, 7.2-725 mg sodium citrate, 35.5-3550 mg hexamethylenetetramine, and 75-7500 mg metal ion salt are added in turn, reacted at 90 degrees C in oil bath for 6 hours, obtained product is washed 5 times using ethanol, to obtain carbon nanotube-based composite metal oxide precursor. The precursor is calcined in inert atmosphere furnace at 400-450 degrees C for 2 hours, temperature is raised at rate of 10 degrees C.minute-1, to obtain carbon nanotube-based metal oxide nanosheet composite energy-storing material. The metal ion salt contains metal ion chosen from zinc, nickel, cobalt, iron and manganese.