A　scalable　dynamic　key　management　scheme,　in　which　pairwise　keys　and　cluster　keys　can　be　updated　securely　and　compromised　nodes　can　be　isolated　timely　from　a　sensor　network,　was　proposed.　The　structure　of　neighbor　table　that　can　help　key　storage　and　update,　is　simple,　with　the　storage　space　for　a　sensor　node　saved.　Using　a　reasonable　clustering　algorithm,　the　scheme　can　integrate　efficiently　with　the　cluster-based　intrusion　detection　schemes　to　improve　the　whole　security　of　a　sensor　network.　Performance　analysis　shows　that　this　scheme　is　very　low　in　computation,　communication　and　storage　overhead.