In recent years, with the increasing development andapplication of wind power technology, the proportion of thewind power in power system is greater and greater. So, theconnection of wind power impacts on power system a lot. Inthe paper, based on the variable speed constant frequencydoubly-fed wind power generator, the IEEE-14 system isinjected to the wind farm. It adopts the method of combinationof steady and transient to analyze and get the maximumcapacity of stability for the wind power system. Simulationresults verify the accuracy of the method and determine themaximum capacity of wind farm.