Abstract: The Internet of Vehicles enables vehicle interconnection and real-time information exchange through wireless communication technologies, providing significant support for enhancing traffic efficiency and driving safety. With the widespread application of IoV technology, balancing identity privacy protection and communication efficiency has become a core challenge. To address the issues of insufficient privacy protection and high computational load in IoV privacy protection, a hierarchical pseudonym-based conditional privacy protection scheme based on blockchain is proposed. Firstly, a "system pseudonym - communication layer pseudonym" dual-layer architecture is designed: the system pseudonym is jointly managed by vehicles and a semi-trusted authority (TA), while the communication layer pseudonym is dynamically generated by regional roadside units (RSUs). Through a decoupling mechanism, the risk of identity association leakage is effectively prevented. Secondly, a certificateless and pairing-free authentication protocol is constructed, using a hybrid key system to separate identity authentication from message verification, reducing reliance on a trusted center and supporting batch verification to reduce communication latency. Finally, an alliance blockchain is introduced to store communication layer pseudonyms and messages, with law enforcement departments (LED) maintaining the integrity of on-chain data to enable the traceable revocation of malicious vehicles. Experimental results show that the proposed scheme, while ensuring vehicle identity privacy, reduces the signature verification time to 1.17 ms compared to existing schemes, keeps the single communication overhead within 168 Byte, and supports efficient batch verification, significantly enhancing the security and practicality of the IoV in dynamic environments.