With　the　rapid　development　of　computation　and　communication　technologies,　the　traditional　vehicle　ad　hoc　networks　(VANETs)　are　changing　to　Internet　of　vehicle　(IoV).　Vehicular　announcement　networks　in　IoV　have　been　widely　used　in　the　communication　of　vehicles.　Generally,　we　need　to　solve　two　problems　while　establishing　a　vehicular　announcement　system.　First,　we　need　to　protect　user＇s　privacy　when　broadcasting　the　message.　Second,　participants　usually　lack　the　enthusiasm　to　reply　to　the　announcement.　To　solve　these　two　problems,　we　propose　a　novel　blockchain-based　incentive　announcement　system　that　not　only　allows　participants　to　anonymously　announce　their　message　on　the　blockchain　in　a　non-trusted　environment,　but　also　motivates　witnesses　to　respond　to　the　request　of　the　traffic　information　with　incentive　mechanism.　Meanwhile,　traffic　messages　and　signatures　in　our　system　are　tamper-resistant,　which　are　recorded　on　the　blockchain.　According　to　the　security　and　performance　analysis,　it　shows　that　our　system　is　privacy-preserving　and　efficient　in　computation　cost.　©　2019　IEEE.