Ecological security assessments in the method and practice have a rapid progress recently. However, due to the lack ofparticularity understanding and systematic analysis forsing with the related abroad concept, characteristics ofreservoir, specific method used in reservoir is still underdeveloped. Referen-reservoir ecosystem werespatiotemporal dynamics and integrated management approach. In view of theseanalyzed, including its special evolution processes,features, the method based on IROW(Inflow-Res-ervoir-Outflow-Watershed) framework was put fornard. four elements were incorporated in the framework, namely the reservoir in-reservoir as proper, reservoir outflow and watershed influence. In additional, some points nn assessment preparation and re-discussion were proposed, especially concerning the sub-regional and sub-period.