Sub-synchronous　resonance　(SSR)　has　become　a　serious　potential　threat　for　both　generators　and　power　grid　in　the　modern　power　system.　To　deal　with　this　problem,　a　voltage　source　converter　(VSC)　based　controller　named　sub-synchronous　resonance　dynamic　suppressor　(SSRDS)　is　proposed　and　designed　by　genetic　algorithm　and　simulated　annealing　(GA-SA).　The　control　strategy　of　the　SSRDS　and　its　mechanism　of　damping　SSR　are　presented　and　analyzed　in　this　study.　To　improve　the　robustness　and　the　damping　effect　of　the　SSRDS　in　the　multi-mode　and　multi-generator　system,　the　GA-SA　is　adopted　to　obtain　the　optimal　control　parameters.　Based　on　the　defined　fitness　function,　the　mathematical　model　of　the　optimization　problem　of　the　SSRDS　is　established　and　well　solved　by　GA-SA　in　MATLAB.　The　nonlinear　simulations　based　on　a　real　multi-generator　system　in　western　China　is　performed　in　PSCAD　to　investigate　the　effectiveness　of　the　proposed　control　strategy.　©　2020　IEEE.