The client of this case is a sophomore girl from a university, diagnosed with borderline personality disorder. The main problems exhibited include emotional regulation disorders, self injuring behavior, attacking others, suicidal impulses, and irrational concerns about self safety. The therapist mainly used rational emotional therapy and mindfulness techniques to intervene in the client’s problems, achieving certain results: the client’s anger and self injuring behavior were reduced, the risk of suicide has been reduced and there has been greater awareness and acceptance of inner emotions.