The rapid development of Internet, machine learning and artificial intelligence, as well as the appearance of a large number of open-source software and communities, has brought new opportunities and challenges to the development of software engineering. There are billions of lines of code on the Internet. These codes, especially those of high quality and widely used contains all kinds of knowledge, which has led to the new idea of intelligent software development. It tries to make full use of code resources, knowledge and collective intelligence on the Internet to effectively improve the efficiency and quality of software development. The key technology is program search and construction, providing great theoretical and practical value. At present, the research work of these areas mainly focuses on code search, program synthesis, code recommendation and completion, defect detection, code style improvement, and automatic program repair. This paper surveys the current main research work from the above aspects, sorts out the specific theoretical and technical approaches in detail and summarizes the challenges in the current research process. Several directions of research in the future are also proposed.