Under the modern corporate system, one of the basic problems of corporate governance is to reduce the agency cost, but it is under the influence of the company’s internal governance structure and external environment. Since agency cost problems in corporate governance have been a research hot spot, this paper teases out a profile of relevant research achievements of agency costs from 2012 to 2017 in China, and summarizes the influence factors and the economic consequences relating to agency cost in the form of literature review. After some discussion and argument, this paper analyses the trend of the existing research and puts forward the future research prospects in this field that is spillover effect of agency costs at the macro micro level.