Disclosed is a method for preparing adrenochrome by catalytic oxidation using nitrogen-doped carbon nanotubes. The method catalyzes dissolved oxygen in an aqueous solution by the nitrogen-doped carbon nanotubes to rapidly oxidize adrenaline, which is completely transformed into adrenochrome. It is a novel preparation process of adrenochrome, which is simple, and has mild reaction conditions, high product purity, an impurity content less than 10−8%, and low subsequent processing cost, thereby having a great application prospect. The nitrogen-doped carbon tubes after use can be regenerated and recovered, and its reutilization is still able to realize the complete transformation of adrenaline. The high utilization rate of catalytic material conforms to the concept of energy conservation, minimizing the costs.