The invention provides a method and a device for optimizing the reactive power of a power distribution network containing distributed generation. The method comprises the steps of setting up a power distribution network reactive power optimization genetic algorithm model according to the preset control parameters of the power distribution network containing distributed generation and a genetic algorithm model, performing load flow calculation on the preset control parameters of the power distribution network to determine the equality constraints of the reactive power optimization of the power distribution network reactive power optimization genetic algorithm model, determining the inequality constraints of the power distribution network reactive power optimization genetic algorithm model according to the positions of controllable transformer taps, each node voltage, the output power of parallel reactive compensation capacity generators and the power factor of the high voltage side of each node distribution transformer in the control parameters of the power distribution network, and generating a reactive power optimization result according to a preset priority parameter, the equality and inequality constraints of the reactive power optimization and the reactive power optimization genetic algorithm model. The method and the device for optimizing the reactive power of the power distribution network containing distributed generation in real time have the advantages that less information is requested for solving problems, the solving process is simple and the optimal solution or the second-belt solution can be obtained with a great probability.