At the same time, the proliferation of Internet information resources and its heterogeneity and dynamics constantly bring new challenges to information retrieval. Information retrieval has become the key to the informationization and various applications of modern society. How to simulate and apply the intelligent principle of human brain at a higher level and fundamentally change the retrieval mode of information resources has become a hot topic in the research of modern information knowledge retrieval theory. Practice has proved that it is a successful experience to combine artificial intelligence technology with information technology and give full play to the role of artificial intelligence. The relationship and development of knowledge retrieval and information retrieval are discussed below. 1. Boolean retrieval is the most commonly used method in modern information retrieval system, which uses Boolean logic operators to logically combine search words or codes. There are three commonly used Boolean logic operators, namely logical OR, logical AND and logical NOT. Using these logical operators, the retrieval phrases are matched into query expressions, and the computer will match the query expressions with the records in the system. When they are consistent, they will hit and automatically output the document record. The following two words "computer" and "document retrieval" are used to explain the meaning of the three logical operators. ① "Computer" and "document retrieval" refer to the documents whose search contents contain both the words "computer" and "document retrieval". ② "Computer" or "document retrieval" refers to searching for documents containing "computer" or "document retrieval" or both. ③ "Computer" rather than "document retrieval" refers to finding the part of the document that contains "computer" but does not contain "document retrieval". Logical operator is the most frequently used in retrieval, and the skill of using logical operator determines the satisfaction of retrieval results. To express retrieval requirements with Boolean logic, we should not only grasp the relevant factors of retrieval theme, but also pay attention to the influence of Boolean operators on retrieval results. In addition, for the same Boolean logic problem, different operation sequences will have different retrieval results. There are many things where Boolean operators are used correctly, but the expected retrieval results cannot be achieved. Second, information retrieval information retrieval originated from the library's reference service and abstract indexing, which first developed in the second half of 19 century. By the 1940s, indexing and retrieval had become an independent tool and user service project of the library. Information retrieval usually refers to text information retrieval, including information storage, organization, presentation, query and access, and its core is text information indexing and retrieval. It is based on information organization forms, such as character strings and structured databases, and uses information processing methods, such as sorting data search and character matching, to achieve inefficient retrieval. Information retrieval comprehensively applies Boolean retrieval method and hyperlink-based retrieval technology, which improves the basic retrieval function, but the disadvantage is that it can not give accurate answers to accurate questions. Historically, information retrieval has experienced many stages of development, such as manual retrieval, computer retrieval, networking and intelligent retrieval. At present, information retrieval has developed to the stage of networking and intelligence. The object of information retrieval has expanded from the relatively closed, stable and consistent information content managed by independent databases to the open, dynamic, rapidly updated, widely distributed and loosely managed Web content. The users of information retrieval have also expanded from the initial information professionals to the general public, including business people, managers, teachers and students, professionals and so on. They put forward higher and more diversified requirements for information retrieval from results to methods. Adapting to the needs of networking, intelligence and personalization is a new trend in the development of information retrieval technology. Third, knowledge retrieval The basic idea of knowledge retrieval is to simulate and expand human intelligent behavior and cognitive thinking methods about knowledge processing and utilization, and it is a favorable tool to make full use of the literature information resources of online libraries and digital libraries. For example, abstract thinking method and image thinking method. Knowledge retrieval has obvious advantages: ① to realize the transformation from information service to knowledge service, to provide users with potential content knowledge, and to analyze and predict advanced field achievements or knowledge. (2) Provide active service mode, automatically optimize users' needs, and actively provide personalized retrieval. ③ User-oriented, flexibly choose ideal retrieval strategies and technologies according to users' needs and changes, and transfer heavy knowledge and information acquisition work from users to computers. ④ Comprehensive application of all kinds of knowledge and efficient intelligent technology to improve retrieval efficiency.