The invention proposes a distributed Newton method based primary frequency modulation control method of a microgrid, and belongs to the technical field of running and control of a power system. The method comprises the following steps of building respective power generation cost function and power generation cost tiny-increasing rate function of each distributed power generation unit; setting an active power output restriction constraint of the distributed power generation unit; exchanging power generation cost tiny-increasing rate information of adjacent distributed power supplies; carrying out Newton iteration by an outer ring iteration method so that power generation cost tiny-increasing rate of power balance and minimum power generation can be figured out, wherein in each iteration step, each distributed power generation unit is used for calculating a Newton direction approximate to the step according to inner ring recurrence and information exchange between adjacent units, so that necessary information is provided for outer ring iteration. According to the method, second-order convergence of the distributed Newton method is fully utilized, primary frequency modulation of the microgrid is rapidly achieved, and the frequency is stabilized; and meanwhile, the minimum power generation cost of the microgrid can be achieved, and the maximum renewable energy utilization rate can be achieved.