Classified retrieval is one of the important factors of library management. It can help readers and administrators quickly find the required materials and better enjoy the convenience of modern network. Through data mapping, hash algorithm can directly convert high-dimensional data into low-dimensional data and store it in Hamming space, which greatly reduces storage consumption and increases computational convenience. For the multimedia retrieval and classification in the era of big data, hash algorithm is right to the point. This paper is aimed at studying the classification and retrieval method of multimedia book cloud resources, extracting different classification categories, determining classification items; cloud resources contain a large amount of image text information, and according to the characteristics of the image text, the features can be well extracted for classification and retrieval, find the optimal book retrieval and classification method, and realize the classification and retrieval of multimedia book cloud resources with the help of hash algorithm. The experimental results show that the hash algorithm can help the classification and retrieval of multimedia books, optimize the classification of multimedia book cloud resources, and improve the efficiency by 20% and user satisfaction by 30%.