Abstract: In order to study the effect of nano polytetrafluoroethylene (PTFE), a electret material, on the space charge characteristics and DC dielectric properties of low density polyethylene (LDPE), nano PTFE powder and LDPE were blended to prepare nano PTFE/LDPE composites with different filler mass fractions (0.1wt%, 0.3wt%, 0.5wt%). The images of SEM show that PTFE particles with a particle size of about 20 nm are well dispersed in LDPE matrix. The crystal size decreases. FTIR shows that doping nano PTFE particles does not alter the original chemical structure of LDPE. DSC shows that the use of nano PTFE particles as heterogeneous nucleating agents promotes heterogeneous nucleation of the material and improves the crystallinity of the composite material. The space charge distribution of nanocomposites at room temperature was measured using the electroacoustic pulse method (PEA), and the conductivity current characteristics and DC breakdown characteristics of nanocomposites were tested. The results showe that nanocomposites with lower doping content can significantly inhibit the accumulation of space charges inside the material, and improve the threshold field strength of space charge injection and the electrical resistance of the material. The thermal stimulation current (TSC) results indicate that when the doping content is low, the trap energy level of the nanocomposite material is the deepest, and as the doping content increases, the trap energy level of the nanocomposite material gradually becomes shallower, and the shallow trap density gradually increases. Finally, the materials studio software is used to simulate and analyze the influence of F atom on the trap energy level of LDPE, indicating that the strong electronegativity of F atom is an important factor affecting the trap energy level of nano PTFE/LDPE composites.