As an important conversational practice posed by ethnomethodologists, “formulation” serves to facilitate the interaction between participants and avoid conversational breakdowns. Based on the “formulation” theory and a corpus with more than 60,000 words transcribed from six psychotherapeutic sessions, this paper investigates the pragmatic types and the interaction structure of formulation in Chinese psychotherapeutic discourse. The findings are: formulation is a common device for cooperative intervention in psychotherapy; the interaction structures of formulation are, on the one hand, an indication of the close cooperation between the participants, on the other, an implication for the unequal distribution of discourse power. As psychotherapists, they can employ formulations to do effecitve therapeutic interventions; as clients, they can use more formulations to strengthen their internal power and improve the therapeutic effect.