A flip-flop circuit using AOI and OAI includes: a MUX unit with a multiplexer selecting between a first signal and a second signal; a master unit with two OAI, wherein the first OAI is coupled between a first node N1 and a third node N3, the second OAI is coupled between a second node N2 and a fourth node N4; a slave unit with two AOI, wherein the first AOI is coupled between the third node N3 and a fifth node N5, the second AOI is coupled between the fourth node N4 and a sixth node N6; and a clock for controlling the two AOI and the two OAI, the clock is connected to the first and the second AOI and the first and the second OAI.