It is very important to improve the control of agricultural inputs to ensure food safety and achieve the goals of reducing fertilizer and drug use. Because of the wide variation in time and space in the supply chain, various regulatory bodies, and limited technical means, some problems occur frequently in the management and control of agricultural inputs. Such problems include irregular accounts, unclear application records, inaccurate information records, and incoherent life cycles. Blockchain technology has the characteristics of decentralization, de-trust, and collective maintenance. It has been applied in many fields such as digital finance, the Internet of Things, intelligent manufacturing, supply chain management, and digital asset trading. Using blockchain technology and the "production–management–application" life cycle of agricultural inputs, this paper proposes a framework for an intelligent management and control platform for agricultural inputs. The framework is composed of data, network, consensus, contract, and application layers. Considering the amount of data that would be handled and the need for security and confidentiality, a dual-mode data storage mechanism consisting of "database and blockchain" was designed. On-chain and off-chain data are associated using a mapping mechanism. Intelligent contracts such as user authentication, qualification verification, account analysis, application warning, and anti-counterfeiting traceability contracts are presented, and their construction is described. Incorporating the advantages of an alliance chain, Hyperledger was used to build the platform. To meet the needs of different participants and be convenient to use, the platform is a combined application system and mobile application, which provides production management, distribution management, application management, intelligent supervision, blockchain management, and other modules. The platform not only enhances the supervision of agricultural inputs, but also improves traceability. Therefore, it provides strong technical support for the regulatory compliance, legal management, and rational use of agricultural inputs.