Abstract: In the era of big data, a great change has taken place in the knowledge environment and information needs faced by the users, which also put forward new requirements for agricultural librarians. Therefore, in this paper, how the agricultural librarians can manage and use the knowledge to carry out the personalized information service in the new period was expounded from the four aspects such as the basic feature of personalized information service, the comparison between traditional book information service and personalized information service, the definition of personalized information service in agriculture, and the case study of personalized information service in agriculture.