Abstract: Flow efficiency (FE) is defined as the ratio of the actual product! vity index of a well to the ideal productivity index for no skin factor (S = 0). Therefore, it is a very important index for judging completion wel1 efficiency of gas and oil wells. However, determination of FE requires the data from build-up curvetesting before .The relationship formula of FE of gas well is derived in this paper, using deliverability equation. At the same time, one point method for determining FH of gas well from the combination of two IPR equations is presented in this paper. Under given reservoir pressure, application of this method oniy requires production rate and flowing bottom-hole Pressure of gas well in a work system.