The invention discloses a preparation method of phosphorus-containing porous carbon nanospheres. The method comprises the following steps: (1) preparing phosphorus-containing polymer nanospheres; (2)preparing phosphorus-containing porous polymer nanospheres; (3) carrying out high temperature carbonization. The phosphorus-containing porous carbon nanospheres prepared by the method has the characteristics of being low in density, large in specific surface area, high in phosphorus content, and the like, thus having potential application prospect in the fields such as electrochemical catalysis, adsorption and energy storage.