There is a widespread phenomenon of trading goods ordered in advance in the commodity market, and consumers choose to imitate others for security reasons, to form a herd phenomenon of following the trend and following the crowd, this has become an important source of default by commodity booking party in transactions, causing a contingent loss to the producer of the goods. In this paper, the influence of the consumer herding effect is introduced into the characterization of default risk transmission, the herding conduction index is added to the intensity-based model of circular default, it makes the description of default risk more in line with the process of outbreak, aggregation and regression of actual risk. With the help of the credit default swap trading mechanism, the cost model of transaction default risk avoidance protocol is given. The simulation results of the model show that the herding effect has an important impact on the default probability of commodity booking party in transactions, it also makes the cost of default risk avoidance have a corresponding direction of change.