With the ubiquitous software application, especially the wide usage of database applications and Web applications, strings have become a more important role in the software programs. At the same time, the program analysis techniques that consider the specialty of strings have been developed, and have been applied to various areas in software engineering. Usually, string value analysis is applied to acquire the possible values of a given string variable. Next, a constraint solver is applied to check whether the values satisfy predefined specifications, so that the correctness of the given string variable can be checked. To further apply string analysis to some security analysis and software maintenance problems, the string analysis is further improved to analyze the possible data origins of a given string variable. This paper presents a survey on string analysis, which mainly introduces the string value analysis, string constraint solving, string data origin analysis, and the applications of string analysis in software engineering.