Packet-like space charge behavior usually induces the electric field distortion and strongly affects the electrical performance of low-density polyethylene. In this paper, we analyze the influence of charge injection, carriers migration and interaction between the free charge and trap in polyethylene on packet-like space charge behavior and introduce the mechanism of Gunn effect to describe the generating process of space charge packet. Based on this, we simulated two kinds of packet-like space charge behaviors with different variation trends and in different applied fields reported by different research groups. The simulated space charge packet shows very good fitting with the experiment data in both packet amplitude and migration velocity. The simulation results also indicate that the injection conditions and trap level depth play an important role in the diversity of packet-like space charge behavior.