In order to solve the low transmission reliability of the Vehicle to Vehicle (V2V) communication in the Internet of Vehicles (IoV), a Minimum Maximum Power-control Evaluation of Transmission Reliability (MMPETR) algorithm was proposed. Firstly, the effect on data transmission reliability of transmitted power control technology in mobile vehicles was studied and it was concluded that successful message transmission probability increased by improving transmitted power.Secondly, current Evaluation of Transmission Reliability (ETR) algorithm was improved by fully considering all the relationships between transmitted power for successfully sending warning message of the send vehicle and the minimum and maximum power of the vehicle itself. Finally, the appropriate numerical values of minimum transmitted power and maximum transmitted power of the send vehicle were given via simulation. The simulation results show that successful transmission probability of MMPETR algorithm is 4% higher than that of ETR algorithm, the MMPETR algorithm can effectively improve transmission reliability of the IoV system.