In this article, the significance of pathological diagnosis in psychoanalysis is explored. It goes from structure to understanding the individual, the certainty of diagnosis and the benefits of the effects of treatment, the exploration of relationship and prognosis. At the same time, a psychiatric diagnosis standard is introduced on the basis of the evolution of psychodynamics to the present taxonomy of symptoms. Whether the relationship between the two is a conflict or convergence is discussed. Furthermore, pathological diagnosis in Freudian psychoanalytic theory and the diagnostic content of DSM-5 of bipolar disorder are discussed in detail. By combining the situation of the author's clinical cases, the different pathological diagnosis methods of bipolar disorder within theories of psychiatry and psychoanalysis and the possible influence on the treatment are discussed in detail, in order to summarise the suggestions conducive to the diagnosis and treatment of bipolar disorder, and to provide reference for the development of clinical psychological work.