Polyethylene (PE) pipes are widely used in oil and gas transportation, municipal construction. Electrofusion (EF) welding is one of the most commonly used connection method for PE pipes. The welding quality of EF joints is crucial to the safety of PE pipeline. Resistor wire is an important part of pipe fittings, and has great influence in final welding quality and strength of EF joints. In this paper, we discussed the influence of resistor wire for EF fittings in the aspect of selection of resistor wire materials and determination of structural dimensions. Resistivity and temperature coefficient of resistance (TCR) are two factors for material selection. In addition, the influence of resistor wire structure, i.e., resistor wire spacing, resistor wire diameter, on the stress distribution of EF joint was discussed through finite element analysis. The results revealed that the maximum stress in EF joint increase with the diameter of resistor wire, and is barely affected by resistor wire spacing.