Abstract: This paper presents a programme of designing 32 bit high-performance adder with semi-dynamic circuit. With modified output carry logic in sparse-tree structure, the semi-dynamic adder circuit, which includes skew-tolerant dynamic domino-circuit and static circuit, and its multiple clocks timing scheme were designed. The different transistors sizes of adder were designed to fit the different loads and drive conditions of the adder. In SMIC 1.8V 0.18μm technology, the simulation results under different conditions show that the designed adder has a high performance.