VANET can provide a wide range of security and non-security related services. However, the existing VANET is difficult to guarantee the QoS of these services. Software defined networking (SDN), which appears in a systematic way, can control network flexibly and separate the data from the control plane, bringing programming ability to the network. Firstly, this paper designs a software defined VANET architecture for heterogeneous multi network access. Secondly, a flow table usage-aware dynamic QoS provisioning framework is proposed, which allows us to manage the network in a modular way and supports the dynamic entering and exiting of the service flows. Finally, this paper establishes a flow table usage-aware QoS routing model with multi-service flows and multi-constraints. The model considers not only the parameters of link state such as packet loss, delay and throughput, but also the service requirements and the flow table usage, and provides VANET application services for a concurrent dynamic QoS routing. Experiments show that QoS routing mechanism proposed in this paper can meet not only the service requirements of their packet loss, latency and throughput, but also the capable of perceiving the usage of flow table so as to avoid the influence of flow table overflow for QoS routing mechanism, which further improves the performance of network QoS.