As a fundamental theory of civil procedure law, the doctrine of object of civil action is penetrating the whole civil proceeding It has determined the target of a lawsuit between courts and litigants, the singular or plurality of the object of civil action, the change and consolidation of actions, and the scope of the fixed validity of judgement A protracted controversy and study about the conception of “object of action” has been arisen among the civil law scholars of different countries The study of object of civil action can be divided into three related stages, which are the stage of traditional substantive law theory, the stage of procedural law theory, and the stage of new substantive law theory But each of the theories has its own advantages and disadvantages respectively, they are being ceaselessly consummated in the progress Regretfully, till now, there has not yet a consistent perspective in the civil law countries