Cascading　failures　are　a　critical　factor　affecting　the　reliability　of　industrial　Internet　of　things　(IIoT)　systems.　Establishing　a　realistic　cascading　failure　model　is　of　significant　importance　for　researching　and　improving　the　reliability　of　IIoT.　However,　existing　research　on　cascading　failure　modeling　for　IIoT　lacks　in-depth　exploration　of　the　actual　characteristics　of　industrial　scenarios,　making　it　difficult　to　accurately　characterize　the　cascading　failure　process　in　IIoT.　In　this　work,　based　on　the　cyber-service　coupling　characteristic　of　IIoT　systems,　we　establish　a　realistic　interdependent　network　model,　taking　into　full　consideration　the　sensing-control　data　flow,　the　service　community　structure,　and　the　diverse　coupling　patterns.　On　this　basis,　a　cascading　failure　model　for　IIoT　is　developed,　considering　the　routing-driven　characteristic　of　the　cyber　network　and　the　production-supply　relationships　among　various　manufacturing　units　in　the　service　network.　Extensive　experiments　are　conducted　to　verify　the　rationality　of　the　proposed　model,　and　some　meaningful　findings　are　also　obtained.