With the continuous expansion of application scopes of Internet of Vehicles, attacks also increase correspondingly. There have been too many attack accidents in IoV. Now the intelligent vehicles have become important targets of a hacker. Based on it, we look forward to constructing a cross-domain security model of IoV. Firstly we introduce the security domain and analyze its divisions. Secondly we study the structure of cross-domain of IoV. Finally we divide the security domain into three layers which are cross-domain application layer, cross-domain network layer, and cross-domain perception layer. Also we study the trust relationship in IoV, and make use of the method of trust evaluation to ensure transactions security and construct a trustworthy environment for cross-domain. Our scheme can partly ensure security of communications and vehicles’ privacy. Next step we will build a test platform and provide test basis for the implementation of secure technical scheme.