The　high-speed　movement　of　Vehicle　Users　(VUs)　in　Cognitive　Internet　of　Vehicles　(CIoV)　causes　rapid　changes　in　users　location　and　path　loss.　In　the　case　of　imperfect　control　channels,　the　influence　of　high-speed　movement　increases　the　probability　of　error　in　sending　local　spectrum　sensing　decisions　by　VUs.　On　the　other　hand,　Malicious　Vehicle　Users　(MVUs)　can　launch　Spectrum　Sensing　Data　Falsification　(SSDF)　attacks　to　deteriorate　the　spectrum　sensing　decisions,　mislead　the　final　spectrum　sensing　decisions　of　Collaborative　Spectrum　Sensing　(CSS),　and　bring　serious　security　problems　to　the　system.　In　addition,　the　high-speed　movement　can　increases　the　concealment　of　the　MVUs.　In　this　paper,　we　study　the　scenario　of　VUs　moving　at　high　speeds,　and　data　transmission　in　an　imperfect　control　channel,　and　propose　a　blockchain-based　method　to　defend　against　massive　SSDF　attacks　in　CIoV　networks　to　prevennt　independent　and　cooperative　attacks　from　MVUs.　The　proposed　method　combines　blockchain　with　spectrum　sensing　and　spectrum　access,　abandons　the　decision-making　mechanism　of　the　Fusion　Center　(FC)　in　the　traditional　CSS,　adopts　distributed　decision-making,　and　uses　Prospect　Theory　(PT)　modeling　in　the　decision-making　process,　effectively　improves　the　correct　rate　of　final　spectrum　sensing　decision　in　the　case　of　multiple　attacks.　The　local　spectrum　sensing　decisions　of　VUs　are　packaged　into　blocks　and　uploaded　after　the　final　decision　to　achieve　more　accurate　and　secure　spectrum　sensing,　and　then　identify　MVUs　by　the　reputation　value.　In　addition,　a　smart　contract　that　changes　the　mining　difficulty　of　VUs　based　on　their　reputation　values　is　proposed.　It　makes　the　mining　difficulty　of　MVUs　more　difficult　and　effectively　limits　MVUs＇　access　to　the　spectrum　band.　The　final　simulation　results　demonstrate　the　validity　and　superiority　of　the　proposed　method　compared　with　traditional　methods.