An operation amplifier (op-amp) and a circuit for providing dynamic current thereof are disclosed. The circuit can be applied to any current op-amp. The circuit comprises two transistors which are simultaneously or non-simultaneously turned on as the input signals respectively received by the first input and the second input of the op-amp get a transition, namely, as the op-amp is in the transient state, so as to increase the bias current at the first input terminal or/and the second input terminal of the op-amp by a dynamic current. Therefore, not only the internal slew rate of the op-amp can be accelerated by the circuit of the present invention, but also the power consumption of the op-amp can not be increased by the circuit of the present invention as the op-amp in the steady state.