The invention belongs to the technical field of soap-free emulsion polymerization, and discloses a method for rapidly preparing microspheres through soap-free emulsion polymerization under a boiling condition. According to the method, an oil phase is formed by using a monomer, an aqueous phase is formed by using an initiator and water, uniform mixing is conducted, heating is conducted to a boilingstate, and reacting under stirring is conducted for forming a microsphere emulsion. The initiator not only plays an initiating role, but also can partially replace a traditional emulsifier to play arole in stabilizing the emulsion. According to the method, no traditional emulsifier is added, so that the use of the emulsifier is greatly reduced, and pollution of the emulsifier to the environmentis avoided while the microspheres with clean surfaces are obtained. Moreover, under the boiling condition, the system is filled with monomer steam and water vapor, so that air in the system can be discharged easily, a nitrogen protection device does not need to be additionally arranged for the system, and certain reaction device simplicity and convenience are provided. The reaction is quick, the required reaction time is short, and the production efficiency is improved.