During the software development and maintenance process, bug fixers usually refer to bug reports submitted by end-users or developers/testers to locate and fix a bug. In this sense, the quality of the bug report largely determines whether the bug fixer could quickly and precisely locate the bug and further fix it. Researchers have done much work on characterizing, modeling, and improving the quality of bug reports. This study offers a systematic survey on existing work on bug report quality, with an attempt to understand the current state of research on this area as well as to open new avenues for future research work. Firstly, quality problems of bug reports reported by existing studies are summarized into a list, such as the missing of key information and errors in information items. Then, a series of work on automatically modeling bug report quality are presented. After that, those approaches are introduced that aim to improve bug report quality. Finally, the challenges and potential opportunities for research on bug report quality are discussed.