Vehicle Terminal is an important part of the IOV(Internet of Vehicle). To improve the reliability and development efficiency of the Terminal software architecture, we designed, referring to NGTP (Next Generation Telematics Pattern), an opening software architecture for the vehicle terminal, in which the IOV system consists of several parts, mobile terminal, background support system, vehicle terminal and background process system. Every part of the IOV system exchange data according to the standard data protocol to complete some typical applications of the IOV, such as remote data acquisition and diagnosis, emergency treatment,remote query and control, etc. The terminal software is decomposed into two parts,function system and guardian system, to improve the reliability. Real-time monitored by the guardian system, the function system will be rebooted upon it breaking down. And the feasibility was verified by the vehicle terminal designed according to this architecture.