For pipelines running across cold regions soil temperature at the depth of buried pipeline would be sub-zero. However a quantities cathodic protection criteria for this situation was not included in both the NACE and ISO standards. In this paper the electrochemical behavior of X80 steel in sub-zero NS4 solutions at different temperature (with ethylene glycol added to avoid freezing) was studied by EIS and polarization curve using a Pt thread as reference electrode. The results showed that with the temperature decreasing the polarization resistance increased and the corrosion current decreased which was the same as the common experience. A polarization potential less negative than -0.85VCSE in the sub-zero experimental environment would be adequate to reduce the general corrosion rate to less than 0.025mm/a as required in NACE standard and 0.01mm/a as required in ISO standard.