Cognitive　Internet　of　Vehicles　(CIoV)　adds　the　cognitive　engine　based　on　traditional　Internet　of　Vehicles　(IoV),　which　can　improve　spectrum　utilization.　However,　Spectrum　Sensing　Data　Falsification　(SSDF)　attacks　pose　a　threat　to　CIoV　network　security.　To　ensure　the　full　utilization　of　spectrum　resources　and　protect　PUs　transmission,　this　paper　combines　blockchain　with　CIoV　to　defend　against　SSDF　attacks　in　the　presence　of　Vehicle　Users　(VUs)　entering　and　leaving　the　network.　Specifically,　this　paper　introduces　a　virtual　currency　called　Sencoins　serve　as　credential　for　VUs　to　purchase　transmission　shares.　And　this　paper　proposes　a　reward　and　punishment　mechanism　and　a　hybrid　Proof-of-Stake　(PoS)　and　Proof-of-Work　(PoW)　mining　model　to　thwart　the　motivation　of　the　VUs　to　launch　SSDF　attacks.　On　this　basis,　this　paper　investigates　the　dynamics　of　SSDF　attack　strategy　choice　of　VUs,　and　uses　the　Largest　Lyapunov　Exponent　(LLE)　to　determine　the　critical　value　of　Sencoins　that　avoids　the　system　to　exhibit　chaotic　behavior.　To　describe　the　uncertainty　of　the　population　proportion　of　VUs　that　choose　different　attack　strategies　due　to　high-speed　movement　and　the　VUs　entering　and　leaving　the　CIoV　network,　this　paper　introduces　Gaussian　white　noise　into　the　replication　dynamics　equation　and　builds　the　Itô　stochastic　evolutionary　game　model,　and　solves　it　according　to　the　stability　judgment　theorem　of　stochastic　differential　equations　and　stochastic　Taylor　expansion.　Finally,　simulation　results　verify　that　the　proposed　method　can　quickly　and　effectively　thwart　SSDF　attacks　in　the　CIoV　network.　And　compared　with　traditional　methods,　the　proposed　method　can　improve　the　efficiency　of　defending　against　SSDF　attacks　by　567%　and　the　average　throughput　by　25%.　　©　2014　IEEE.