With the rapid development of Internet of Vehicles, cellular network and vehicular dedicated network will coexist to form heterogeneous networks. Varies applications for vehicles will generate huge volume of data. Under this foreseeable circumstance, handover mechanism is crucial to guaranteeing the quality of service (QoS) of vehicles. Due to the vehicles' high-dynamic feature, the attributes needed for handover decision making are time-varying, thus the handover methods based on network snapshot in existing works are not applicable anymore. It requires more insights on network and vehicle dynamics for practical handover decision making. To solve this problem in this paper, we propose an intuitionistic fuzzy handover mechanism for heterogeneous vehicular networks. Especially, we design an intuitionistic fuzzy based algorithm for network selection in the handover mechanism which is suit for time interval decision making. Under the IEEE 802.21 media independent handover framework, we design an efficient information exchange mechanism to make the network end information available for vehicles. Simulations results demonstrate the proposed mechanism outperforms existing mechanisms with less number of handover times and better QoS.