The article first analyzes the concept and connotation of "prompt engineering" and compares it with the library information retrieval process. It then provides a definition of the prompt engineer librarian. Finally, it explores the functional responsibilities and training recommendations for prompt engineer librarians. This paper argues that there are many similarities between prompt engineering and library information retrieval, such as the need for precise language expression to achieve specific information retrieval or generation goals. It reviews the functional responsibilities of prompt engineer librarians based on the requirements of AI technology companies and library training programs. Finally, this paper proposes cultivating prompt Librarian from four aspects: skill integration, tool empowerment, user collaboration, and ethical literacy. This includes integrating retrieval skills into prompt engineering, constructing a localized prompt optimization platform, driving prompt iterations with user needs, and establishing an ethical assurance system. These measures aim to address the challenges posed by generative artificial intelligence technologies.