Abstract: In order to overcome the defect of conventional static CMOS circuits at high frequency,MOS current mode logic circuits were introduced.MOS current mode logic is a kind of differential symmetric logic circuits.Its power consumption is relatively low at high frequency compared to conventional CMOS logic,and it has typical high speed and low power character.MOS current mode logic circuits with different input terminal were analyzed,then two circuit structures were proposed to realize MOS current mode logic full adder and the application were given for different circuit structure.The simulation results verify the effectiveness of circuit structure.