Abstract: Replacing business tax with value-added tax (VAT) in pipeline transportation industry initiated from August 2013 has direct impacts on economic assessment for new projects. Based on this, taking the oil and gas pipeline engineering projects as an example, this paper discusses the impacts of the replacement on economic assessment of projects. The differences between business tax and VAT are reviewed. With consideration to specific features of economic assessment for pipeline engineering projects, differences in capital assets, business revenues, business tax and additional charges, profits and cash flow before and after the replacement are analyzed one by one. Precautions for value assignment and associated calculation for data used in statement of cash flow for project investment, estimation of total costs and other statements are summarized.