Biological neural networks system is composed of a number of neurons through synapses between each other, transmitting electrical signals through the synapse, and has a very complex nonlinear network system. In this paper, the Spiking Neural Networks (SNN) model is constructed to simulate the real neuron discharge behavior. First, the SNN model is established based on the Integrate-and-Fire (IF) mechanism. Then, the parameters of the model are determined, and then the simulation of a neuron and a plurality of neurons is carried out. Finally, compare between model simulation and real neuron discharge behavior. The simulation result shows that the biological neural networks based on the IF model can be used to approximate the real biological neural networks.