The invention discloses a method for calculating the rotor forced excitation hot spot temperature of an air-cooled non-salient pole synchronous phase modifier, and the method comprises the steps of inputting a calculation model and forced excitation parameters, and dividing a model geometry into a discretized heat flow node topological connection diagram; and gradually determining the area, depth,thermal resistance, resistance, heating power and other parameters of each heat flow node, listing the energy conservation equation of each node by taking the node temperature as an unknown variable,forming an equation set, and solving the equation set to obtain the rotor winding forced excitation hot spot temperature of the air-cooled phase modifier. According to the invention, only 24 parameters need to be input, the rotor forced excitation hot spot temperature can be automatically calculated, the heat flow node topological graph can be automatically drawn, the requirements for air coolingnon-salient pole synchronous motor rotor forced excitation hot spot temperature calculation and curve drawing can be well met, and the purpose of conveniently, rapidly and accurately obtaining the air cooling rotor forced excitation hot spot temperature is achieved. The invention has the characteristics of less input data, simplicity and convenience in operation, quickness in calculation and drawing, concise and intuitive heat flow node topological connection diagram and the like.