Abstract: To solve the problem of the low data transmission rate due to the selfish behavior of relay users in vehicular cooperative communication, an optimal relay selection algorithm based on credit card risk assessment is proposed. At the first, a D2D relay cooperative two-layer (social network and physical layer) model is set up to describe the human behavior characteristics of the vehicle nodes. And then, the relay’s trust is evaluated by applying the credit risk assessment mechanism from business requirements perspective, relay’s credit levels are rated by the decision theory. On the other hand, the relays with good credit are compensated and motivated from the relay’s perspective. Finally, the optimal relay with high trust and reasonable price is selected. The numerical simulation results show that the data transmission rate of the proposed algorithm is increased about 10% compared with those that only the active relays are selected.