Cooperative　beamforming　and　jamming　are　two　efficient　schemes　to　improve　the　physical-layer　security　of　a　wireless　relay　system　in　the　presence　of　passive　eavesdroppers.　However,　in　most　works　these　two　techniques　are　adopted　separately.　In　this　letter,　we　propose　a　joint　cooperative　beamforming　and　jamming　scheme　to　enhance　the　security　of　a　cooperative　relay　network,　where　a　part　of　intermediate　nodes　adopt　distributed　beamforming　while　others　jam　the　eavesdropper,　simultaneously.　Since　the　instantaneous　channel　state　information　(CSI)　of　the　eavesdropper　may　not　be　known,　we　propose　a　cooperative　artificial　noise　transmission　based　secrecy　strategy,　subjected　to　the　individual　power　constraint　of　each　node.　The　beamformer　weights　and　power　allocation　can　be　obtained　by　solving　a　second-order　convex　cone　programming　(SOCP)　together　with　a　linear　programming　problem.　Simulations　show　the　joint　scheme　greatly　improves　the　security.