Abstract: The usage of the auxiliary word “lai” in the Chinese text book Lao Qida can be categorized into three classes: auxiliary of approximate number, modal auxiliary and situational auxiliary. The first class can be used to express both approximate number and time. The second may appear in the statements, questions and imperative sentences and can express various modalities. The third class can express the past situation. In addition, it can be used to express the pure change of situations as well as completion of action.