The pertinent choice of flip-flop topologies is an essential importance in the design of VLSI integrated circuits for high speed and high performance MODFET circuits. Understanding the suitability of flip-flops and selecting the best topology for a given application is an important issue to fulfill the need of the design to satisfy low power and high performance circuit. This paper enumerates high speed design of JK- flip-flop using AlGaAs/GaAs MODFET. The proposed flip-flop is having less number of transistors than existing designs. Simulation results show lowest average power and least delay than existing designs.