Abstract: Nano-SiC/low density polyethylene (LDPE) composites with different nano SiC mass fractions (0.5%, 2.0%, 3.0%) were prepared by melt blending method. Effects of nano-SiC particles on dielectric properties of LDPE were studied. Dispersion character of nano-SiC particles was observed by SEM. Space charge distribution character of nano-SiC/LDPE composites under 40 kV/mm field strength was obtained by using pulse electro-acousitc(PEA)method. Thermal simulated current (TSC) was also employed to further identify that nano-SiC can increase the trap density of LDPE. The results show that nano-SiC particles disperse uniformly in LDPE and there is no larger agglomeration. The quantity of injected space charge of nano-SiC/LDPE composites with nano SiC mass fraction of 0.5%, 2.0% and 3.0% are much lower than that of LDPE. After short circuit 600 s, the residual space charge density is much smaller than that of LDPE. The quantity of injected space charge and conductivity of nano-SiC/LDPE composites both reduce with the increase of nano-SiC particles. The nonlinear coefficient of electric field of nano-SiC/LDPE composites with nano SiC mass fraction of 3.0% is 2.6, which is much smaller than that of LDPE of 4.3. TSC curves show that a large number of traps appear in nano-SiC/LDPE composites, which inhibit the transportation of carriers in material, thus hinder the migration and accumulation of space charge.