Abstract: Through the analysis on risk recognition, risk factors, risk evaluation, risk management and the corresponding measures,this paper tried to construct the risk prevention system, to guide the normal operation of library information ecology circle. Based on the existing research results,it used the information ecology theory,risk management theory and logical analyses,to explore the risk performance and cause, and proposed the risk prevention measures in the library information ecology circle. The risks of library information ecology circle were mainly construction risk, operation risk and the risk of service output. The risk prevention should take measures to change from manpower intensive to knowledge intensive, from order resource to open access, from traditional service to embedded subject service, from the literature information service to digital knowledge service, from the fixed users to mobile users.