The letter security carrier in-place control system strengthens the centralized storage and control of classified carriers, focuses on prevention, strengthens supervision, facilitates the use and management of classified carriers and ensures the confidentiality and security of classified carriers on the premise of meeting the confidentiality requirements at all levels. In the process of using existing classified carriers, there are such problems as manual registration of accounts, which is labor-intensive and time-consuming, unintuitive collation and use, overdue use that can't be detected in time, and heavy workload in manual inventory. In order to solve the above problems, the use of electronic tags and identification systems supports the intelligent identification and entry of daily documents, notebooks, mobile hard disks, USB flash drives, cameras, recording pens and other classified carriers, as well as tracking and positioning, keyword retrieval, borrowing and reading management, carrier recycling, reminder of return, and alarm of violations, so as to enhance the efficiency of classified carriers' storage and management.