To solve the problems of line-of-sight link blocking and limited resources in urban road IoV, this paper proposed a resource optimization strategy based on intelligent reflecting surface(IRS) in hybrid communication IoV scenarios, which constructed an IRS-assisted IoV system, and used D2D technology to increase the data transmission capacity of vehicles that were far away from the base station(BS) in this system. In order to improve the spectral efficiency of the system, this system introduced CR technology, allowing D2D users to underlay into the BS user channel and transmit data without exceeding the preset interference threshold for BS users. For the constructed IRS-D2D hybrid communication IoV system model, this paper proposed a finite resource optimization allocation problem based on maximization of system sum rate. To achieve system sum rate maximization, this problem jointly optimized the power allocation, IRS phase shift and spectrum resource allocation under the condition of satisfying the users communication quality of service(QoS). Since the optimization problem was a multivariate mixed integer non-convex problem, which was difficult to find the optimal value in polynomial time, the optimization problem adopted a two-stage joint allocation scheme. Specifically, in the first stage, optimize power allocation and IRS phase shifted by using the slack variable method to obtain a local optimal solution. In the second stage, it employed an alternating optimization algorithm for spectrum resource allocation. Simulation results show that the IRS assisted resource optimization strategy improves system sum rate and spectral efficiency, outperforming existing schemes. Consequently, IRS-D2D communication technology proves to be a viable solution for IoV.