The aim of this study is to investigate dynamic characteristics of late wave of auditory evoked potentials (AEPs) in synaptic malfunction rat model. Two dynamic characteristics relative to cognitive function were investigated which are dynamic latency and dynamic amplitude of P1. Synaptic malfunction model was made by Sprague-Dawley rats via microinjecting beta-amyloid protein (A-beta) into hippocampal CA1 area of rat. Dynamic AEPs with high background noise were recorded for both model and normal rats in experiments. Dynamic late wave were taken from dynamic AEPs using third-order correlation and wavelet technology. The dynamic-average latency and the dynamic-average amplitude of P1 in a small time window (5s) were performed as dynamic index in this study, which remain most of dynamic information because the average window was very small. Then dynamic-average latency and the dynamic-average latency of P1 were compared between synaptic malfunction rat and normal group. The results of this study have demonstrated that: (1) the dynamic-average latency of P1 for model rats prolonged remarkably than control (P<0.01, alpha =0.05); (2) the dynamic-average amplitude of P1 for model rats increased remarkably than control(P<0.01,alpha =0.05). The conclusion is that dynamic-average latency and dynamic-average amplitude in the synaptic malfunction rats model has obvious difference with normal group.