Information transmission goes through the entire process of social risks spreading, which is largely influenced by governmental governance. This paper, in terms of the relation between information transmission and social risks, elaborates the necessity of information management, and establishes a social risk information transmission model based on classic transmission models combined with the major position of government in information management, which is used to study the impact of governmental governance on social risk information transmission rules. Simulation study which is conducted on cases of social risk management of engineering project suggests that governmental governance on information management prolongs its reaching peak and stability of risk information transmission, helpful in mitigating social risk transmission. Administration and positive response can increase the proportion of the susceptible in information transmission system, and decrease the proportion of infected and the potential reaching peak, both mitigating social risk information transmission simultaneously. Positive response is more effective to impact the parameters of information transmission system. The paper presents suggestions on policies from the entire information flowing process of information collection, processing and distribution.