The intelligent software development is migrating from simple code retrieval to semantic empowered automatic code generation. Traditional semantic representation cannot effectively support the semantic interaction among people, machines, and code. It becomes an urgent task to design a set of machine-readable semantic representation. In tThis paper, westudy firstly points out that code knowledge graph forms the basis to realize the intelligent software development, and then analyzes the new features and new challenges of intelligent software development based on code knowledge graph in the era of big data. Next, we review the research progress is reviewed both in intelligent software development and in code knowledge graph. It is noted that the current research of intelligent software development is still at a preliminary stage. Existing studies of knowledge graph mainly focus on open-domain knowledge graph, and they cannot be directly applied to code and software development domain. Therefore, we discuss the new research trends of code knowledge graph are discussed in detail from five aspects, including namely modeling and representation, construction and refinement, storage and evolution management, semantic understanding, and intelligent application, which are essential to meet the various types of demands of the intelligent software development.