Abstract: The principle of "sufficient" current amplitude differential protection was proposed to reduce the pressure of communication and to enhance the economic efficiency for distribution network with distributed generation（DG）. An optimized comprehensive current amplitude comparison criterion was set up by using different current amplitude information including phase current, sequence current and variation of current amplitude. This paper studied several factors influencing the sensitivity of the criterion such as internal angle difference, DG terminal voltage drop, transition resistance and fault types. It was found that the comprehensive criterion had better resistance to DG terminal voltage drop and transition resistance compared with only using phase current criterion and it also had better self-adaptability to symmetrical faults. Finally, the conclusion of the theoretical analysis was verified by Simulink simulation.