Starting from the origin of traffic risk, this paper analyzes and extracts the attributes of traffic elements, reveals the influence mechanism of man vehicle road on driving risk, establishes the diffusion theory of driving risk, reveals the evolution law of driving risk, establishes the diffusion model of driving risk, and puts forward the dynamic identification method of driving risk. Taking the mutual coupling traffic system of human vehicle road as the research object, the comprehensive risk identification is constructed Identify and quantify the evaluation model to realize dynamic and quantitative risk identification in complex scenarios.