The adequacy of generatorsreactive power reserve is explained from the viewpoint of maintaining static voltage stability of power systems，and a new definition of generatorseffective reactive power reserve is proposed.The method for analyzing the composition of generatorsreactive power reserve is outlined，and the mathematical model for obtaining minimal generatorsreactive power reserve is set up along with an approximate solution framework.Case studies are conducted with a practical power system，and the results of the proposed method are discussed and compared with those of static voltage stability analysis and control.The significance of generatorsreactive power reserve analysis in practice is well demonstrated.