It is reported that software configuration failure has become an important factor causing computer system anomalies and crashes. Configuration failures are caused by users' misconfigurations due to their inability to adequately obtain configuration constraint information. Because users lack software domain knowledge, configuration failures are difficult to avoid. Therefore, how to accurately analyze and extract the constraints of software configuration items to provide a basis for software configuration fault diagnosis and repair has important research significance. Specifically, enumeration is a common type of software systems, and the limitation of its value space often causes the system software configuration failure. This paper systematically investigates the enumeration type configuration constraints of six commonly used C/C++ open source software including Apache Httpd, Nginx, Postfix, MySQL, Redis, and PostgreSQL. Aiming at the problem that the value spaces of enumeration type configuration items are underreported in the previous methods, based on the program analysis method, an automatic configuration constraint extraction method for enumeration type configuration is designed and implemented. This method greatly improves the accuracy of the configuration constraint extraction of the above open source software, and improves the availability of the software configuration, and the diagnosibility of configuration failure.