The invention relates to a method for setting parameters of a robustness fractional order PD< mu > controller based on a vector quantity method, and belongs to the technical field of fractional order automatic control. A mathematic model transfer function of a controlled object system is given, a controlled object is written into a controlled object vector quantity mode, a performance index vector quantity mode is written out, a controlled object vector quantity P is corrected through a correction vector quantity L to reach a performance index vector quantity G, the correction vector quantity and a controller vector quantity form a triangle in a complex plane, and a differential coefficient to be set is obtained. The method can reduce calculated quantities, the setting process is simple and easy to understand, and when the controlled object is changed, users only need to calculate the module value, the phase angle and the angular speed of the controlled object, the following formula can be used indiscriminately, and therefore the process of repeatedly deducing an equation is reduced, and the multi-solution problem existing in matlab solutions is solved.