The conductivity and mechanical properties of carbon black (CB) filled polyethylene (PE) composites depend on the conductive filler, molecular structure of polymer matrix, and the processing methods which are applied. CB filled high density polyethylene without and with glass fibre (GF) composites have been manufactured using single and twin screws extruder. The composite made from the single screw extruder showed a much higher conductivity than that made from twin screws extruder for CB/PE composites with and without glass fibre. The conductive paths are formed at very low CB content (1wt% CB for GF/CB/PE) when using single screw extruder to manufacture. The microstructure of these composites were analysed using SEM.