More　standardized,　networked　and　intelligentized　nature　of　industry　4.0　has　intensified　critical　infrastructures　cyberthreats.　According　to　cyber-physical　systems　(CPS)　layered　architecture　and　security　requirements　in　industry　4.0,　a　cyber-physical　systems　testbed　based　on　cloud　computing　and　software　defined　network　(SDN),　or　CPSTCS　is　proposed.　The　CPSTCS　uses　a　network　testbed　based　on　cloud　computing　and　SDN　to　recreate　the　cyber　elements　of　cyber-physical　systems　and　real-world　physical　devices　for　the　physical　components.　The　CPSTCS　helps　assess　cyberthreats　against　the　cyber　and　physical　dimensions　of　critical　infrastructures.