Abstract: State assignment has close relationship with peak current of finite state machines(FSMs).High peak current may result in circuit failure.Against this issue,two peak current optimization methods are proposed based on FSM state assignment.1) A new cost function including switching power and peak current is proposed and a genetic algorithm(GA) based state assignment method is proposed to optimize both power dissipation and peak current.2) First,a power optimized state assignment is obtained by GA,then a SAT-based heuristic algorithm is proposed to re-encode the solution to optimize peak current.The algorithms have been applied to LGSynth93 benchmarks.The experimental results indicated that the first method can reduce peak current efficiently traded with slight power dissipation increase,the second method can reduce peak current significantly with no extra power dissipation overhead.Furthermore,the latter method can be integrated in various FSM power optimization algorithms and implement both low power and low peak current simultaneously.