The focus of dynamic data security protection of IoT (Internet of things) is to reject tampering of unauthorized users, meanwhile, to realize the process in evidence and track tracing of the dynamic data operation of IoT. In order to solve the problems such as secure storage and sharing of dynamic data generated by a large number of IoT devices, firstly, a mathematical model for the security of dynamic data storage was established, as well as dual consortium chain structure is proposed to realize multidimensional authorization and dynamic data storage of operational entities. Then, a consensus algorithm based on VNL (verification nodes list) was proposed. After that, an optimization scheme of dynamic data traceability mechanism based on consortium block chain was put forward. Finally, through open experiments and performance analysis, it shows that when the eigenvalue of the operation entity authorization is 64 and the number of IoT operation entities is less than 106, the succeed probability of the attacker is almost 0. Meanwhile the proposed scheme can effectively avoid potential attacks on dynamic data, such as double output attacks, replay attacks and hidden attacks and so on. Thus it can effectively prevent the attackers from unauthorized manipulation of the IoT, such as tampering or counterfeiting under approved accession mode. The scheme has good application value while ensuring the dynamic data storage security.