The unreal joint obligation originated in Germany. It is a civil law system developed on cases, and has played a tremendous role in the early civil law practice. But unreal joint obligation theory was questioned a lot since the date it was proposed. It has been developing in a winding path. Especially the prosperity of contemporary civil law theory and system brings a greatly compression to the area of application of the unreal joint obligation. This paper reviews the theoretical and practical developing history of the unreal joint obligation, introduces and comments the affirmative and negative view of the unreal joint obligation and their basis, eliminates the unreasonable elements of traditional unreal joint obligation theory, demonstrates the contemporary existing value of the unreal joint obligation, redefines the types and scope of its application, and puts forward some suggestions about how to construct the unreal joint obligation system under the contemporary civil law theory and system.