This　paper　begins　with　a　discussion　of　the　role　and　value　of　network　testbed　which　apply　a　universal　experimental　platform　to　test　new　theories,　new　technologies,　and　new　vulnerabilities　for　cyber　security　research　of　networked　systems.　Several　common　aspects　of　NCR,　Emulab,　Testbed@TWISC,　DETERlab,　PlanetLab,　SATURN,　StarBED　and　GENI　are　introduced,　mainly　including:　background,　techniques,　and　architecture.　Finally,　we　propose　the　research　trends　of　network　testbed,　on　the　one　hand　are　the　integration　of　cloud　computing,　software　defined　network　(SDN)　and　test　kits　in　self-improvement,　on　the　other　hand　are　extended　to　Cyber-physical　systems　(CPS)　testbed.