Failure science is a new branch in management idea. Because the deep pit project failure is normally in practice and the soil is more complex than the upper structure, the failure science is suitable to it. By dint of many failing projects, the failure knowledge becomes scientific technological information, and factors of risk cause can be studied. Then the place and roles of probably failure and risk cause factors are determined. So the failure can be avoided. For any failure projects, there must be some reasons of management. In this paper, a case is studied by failure cause tree analyzing method. For engineering failure which has taken place, while the path, causes and condition of the failure are comparatively certain, the structure of failure tree is comparatively determinate and perspicuous. By analyzing the process of failure, the reasons of failure are clear. Because there are many kinds of project failure in practice, the different failure type can be used by different failure cause tree analyzing logical figure.