In order to reveal the complexity and uniqueness of open government data risk and enhance the recognition and response ability on it, this paper illustrates, based on the methods of literature study and comparative analysis, the connotation of open government data risk from cognitive belief, stakeholders, disclosure content, technology and regulatory system. It also analyzes a series of negative impacts of open government data risk on data open process, data management order, data ecology and data management cost. Meanwhile, it introduces the practice of developed countries on the risk identification and prevention of open government data, sorting out the current difficulties of it, and then points out concrete countermeasures on how to create a risk identification and prevention mechanism on government data releasing.