The four principles of collection construction are organic connection principle, benefit principle, characteristic principle and flexibility principle. Collection construction, also known as library collection construction, is the whole process of systematically planning, establishing and developing the collection system according to the tasks of the library and the needs of readers. Its goal is to form a knowledge system with specific functions through careful selection and organization. The construction of library collection itself is an academic creation, and people engaged in this work are called architects of knowledge buildings.