As a new service mode, cloud services become the growth point of the service innovation of agricultural information institutions. This paper presents three-layer cloud service model of agricultural information institutions which includes infrastructure layer, automated management system layer and service layer from bottom to top. Based on this model, this paper studies the cloud service mode and construction content of agricultural information institutions from four angles of IaaS, PaaS, DaaS and SaaS. Finally, the cloud service mode facing internal member institutions and readers of the national science and Technology Library is designed to verify the cloud service model.