Abstract: Considering referred value of pipeline's annual cost as the object function, object function equations of economic technology calculation for fiberglass-reinforced plastics pipeline are established.Based on analysis of the variation relationship, it is considered that flowrate and pipe diameter directly influence the construction cost of water pipeline.According to classification of water transportation forms, calculation and analysis on economic pipe diamter for pressure pipeline and gravity flow pipeline are made.Conception of algorithms flowrate are introduced in the calculation, and approach optimized equations for water pipeline are given.