Abstract: The internal corrosions can not be avoided although external protection is always given by the coatings and CP for the idled long distance pipelines. Three plugging technologies are set forth in the light of the characteristics of long distance pipeline, and a plugging test simulating long distance pipeline has been made. The results showed that the water/gas plugging technology, by which proper inhibitor is added to the pigging water, can inhibite effectively corrosions occured to steel pipes within the plugging period. The inhibitor can control water phase corrosions and/or gas phase corrosions in the case of evaporating into a gaseous state. The test results from electrochemistry showed that the plugging liquid added with inhibitor can prevent the internal surface of the pipe wall from corrosions. This plugging technology is considered practical with its operability, low cost and good economical benefits.