This invention relates to a hydrophilic and lipophilic carbon nanotube and its preparation method. Adopting the idea of physical coating modification, after ultrasonic-assisted purification under acidic conditions, polyvinylpyrrolidone (PVP) and its block polymers are introduced onto the surface of the carbon nanotubes under the action of an initiator and at an appropriate temperature, thereby obtaining carbon nanotubes with quantitatively hydrophilic and lipophilic groups on their surfaces. Carbon nanotubes containing this structure have good dispersibility in water, organic solvents, and polymer matrices, thereby improving the dispersibility of carbon nanotubes. The provided preparation method is simple and feasible, characterized by controllability and quantification; the obtained carbon nanotubes with quantitatively hydrophilic and lipophilic polymers on their surfaces have good processability, paving the way for the application of carbon nanotubes in fields such as composite materials, hydrogen storage, electronic devices, sensors, and biomaterials.