Abstract: Based on the case analysis, the paper points out that from the view of whether it can be counted, environmental impact caused by pipeline engineering transporting refined oil can be classified into three types: the first is "can be counted accurately", the second is "difficult to count accurately" and the third is "its cost is too huge to be counted". This kind of classification on valued environmental impact is favorable to compare cost with benefit, to promote constructor of pipeline to make measures to protect environment initiatively and scientifically.