The embodiment of the invention discloses an all-digital bionic circuit and system applied to neurons. The circuit comprises a neuron input module, a clock selection module, a counting module, a zerosetting delay module and a neuron output module, wherein the counting module is provided with a pulse signal input end, a clock signal input end, a zero clearing end and a counting signal output end;the neuron input module is connected with the pulse signal input end; the clock selection module is connected with the clock signal input end; the zero setting delay module is connected with the zeroclearing end; and the neuron output module is connected with the counting signal output end. Based on the embodiment of the invention, upward or downward counting of neuron signals can be dynamicallycarried out in a neural network, zero setting signals and counting signals can be broadened through the zero setting delay module, and the refractory period of the neurons is simulated, so that data in the counting module is cleared. The bionic circuit adopts an all-digital design, so that the complexity of the circuit can be simplified, the power consumption of the circuit can be reduced, and large-scale circuit integration can be conveniently realized.