Abstract: Disk friction loss has great effects on the performance of centrifugal pumps, especially on the performance of low specific speed centrifugal pumps. So to calculate it correctly is very important and is one of significant bases for characteristics prediction of centrifugal pumps. Although there are many kinds of disk friction loss formulas, practical computation indicates that the results of these formulas are not exact and the windages can not be neglected. In this paper, different disk friction loss formulas are compared and the paper concludes that disk friction formula should be chosen according to specific speed. Based on the excellent centrifugal pump model, the chosen formulas are amended by regression analysis and the calculation coefficients are given in the ways by specific speed, capacity and revolution speed. At last, seven centrifugal pump models are chosen to check up the regression analysis results and the practical application indicates that the regression analysis results are exact and the results offer a new and exact calculation method for engineering practical application.