Software intelligent development has become one of the most important research trends in software engineering. In this paper, we put forward two key concepts - intelligent development environment (IntelliDE) and software knowledge graph - for the first time. IntelliDE is an ecosystem in which software big data are aggregated, mined and analyzed to provide intelligent assistance in the life cycle of software development. We present its architecture and discuss its key research issues and challenges. Software knowledge graph is a software knowledge representation and management framework, which plays an important role in IntelliDE. We study its concept and introduce some concrete details and examples to show how it could be constructed and leveraged.