Different selection of rated capacity and charging/discharging power parameters will directly affect the power supply quality and system reliability for an isolated wind-diesel-storage system（WDSS）.In order to meet the power supply adequacy of WDSS and improve the system economy，suitable energy storing devices（ESD）selection should be made.Thus，a method for the selection of a wind turbine generator（WTG）type in a WDSS is presented based on the meeting degree of power output of WTG to load.A forward/backward sweep method for ESD selection is presented based on the power supply adequacy of WDSS，and an adequacy evaluation model for an isolated WDSS is developed.Comparisons between the proposed method and the traditional adequacy evaluation algorithm have verified the correctness and validity of the proposed method.