Since 1996, changes have occurred within the Chinese criminal compulsory measures system. The condition and time limit for criminal detention is one measure of change. However, over the years many questions have arisen in practice with issues like “extended custody,” “covert custody,” and “long custody without decision.” As a new attempt in the study of compulsory measures, analysis in this paper focuses on the issue of “unsettled custody.” In the Western legal system this is referred to as pretrial detention. The intent of detention is to deprive active criminals or major suspects of their personal freedom. This paper discusses the nature of pretrial detention, the time limit of pretrial detention and extension, ways of remedy for pretrial detention, place of pretrial detention, thoughts about control of pretrial detention, and the difficulties in the reform of the pretrial detention system.