The relationship between the client and the defense counsel is the central part in the Model Rules of Professional Conduct.Compared with the contract established by the client and the defense counsel on the basis of civil consultation, the counsel’s professional conduct standard has claimed higher requirements for the defense counsel. These requirements are reflected in aspects of the contract between the client and the defense lawyer, such as the establishment of relations, the allocation of rights, the resolution of the conflicts of interest, the termination of relationships and so on. The defense counsel’s loyalty to the client and the obligation to safeguard the justice are the two basic concepts all the time, of which the first is the core and the second is the boundary for the counsel’s action.In the urgent need of the Model Rules of Professional Conduct in China, American Model Rules of Professional Conduct and related principles have great enlightening significance to the construction of professional ethics of lawyers in our country, such as the emphasis on the duty of loyalty and the introduction of the effective defense.