Software projects face a common problem that time is always not enough, and only a few projects can be finished on schedule and within budget. Projects often need to accelerate the progress to compensate the laggard portion, or to compress schedule to accommodate to the market competition. Opposite to the generality of the problem, researchers didn¡¦t focus on this field, and the quantitative studies had low degree of explanation. To study the issue, this thesis used the qualitative case study to interview four development teams. It is to understand how the compression methods of the teams work, and induce to three dimensions, including management, development process, and team structure. These teams have fundamentally different characters in order to find the most representative cases in limited samples. Finally, this thesis comprehends how the compression methods work, and how the teams use compression methods under which project characters. In addition to comparing the results with prior literature, new compression methods are also discovered. The final results of this research could serve as guidelines to the development teams that face the problem of schedule compression.