Current situation of agricultural informatization at home and abroad was studied in the paper. Using agricultural information knowledge base, and taking the information of agricultural industrial chain as the core, agricultural policies, information technologies, standards and other information categories were deeply researched. The open agricultural information knowledge base in big data era was constructed, which fulfill the functions of agricultural resource integration, sharing, analysis and utilization. And it also laid a solid foundation for helping to achieve agricultural production decisions, prevention and warning of agricultural pests and diseases, agricultural product output and price forecasts, and so on.