To Clarify The Cocept Of The Ego In Freud

'what I am?' 'who I am ' 'where did I come from?' all of questiones need to be answered in the philosophy ,the religion and the psychology .Psychoanalysis as a kind of knowledge and practice about the mankind also concernes and responds to these questiones.In the history of psychoanalysis ,since the concept of the ego was come up , it is concerned in all the time, especially in Freud . Freud raised the concept of the ego in his earlier phase, then gave it more and more attention .The concept of the ego has a close connection with the cause of the neurosis and the symptom, so it is necessary and important to classify and talk about the concept of the ego .on the basis of understanding of the concept of the ego ,I clarify it in three categories and have a talk: dynamically, the ego has the function of the defence, for which the ego put the repression ,the resistance ,anxiety and other defensive mechanisms into operation, the funtion of the ego influences the form of the symtoms ; economically, the ego as an organization supervises thecathesis of the libido ,and I have a talk about the four groups conceptions-the instinct of self-protection and the sexual instinct ,the ego instinct and the object instinct ,the ego libido and the object libido ,the life instinct and the death instinct topographically, the ego as an agent deals with the relationships with the id ,the super-ego and the reality.in the conclusion ,according to the theory of Lacan and Huo datong ,I try to understand Freud again.