Abstract: This paper proposes a dynamic security authentication scheme based on public key infrastructure（PKI） and ISO 14229 standard UDS-0x29 services, and briefly introduces its practical application in the development of automotive diagnostic software on PC and Android. The solution builds a tripartite collaboration system of cloud certificate center, diagnostic software and vehicle ECU, realizes dynamic security authentication of diagnostic instrument and ECU based on UDS-0x29 service, realizes refined control of vehicle read/control/brush and other operation control permissions, and provides dynamic and comprehensive full-link security protection for intelligent vehicle controller communication.