A highly efficient flow discharge measuring method was proposed in this study. Either the traditional velocimeters or the Acoustic Doppler Profiler (ADP) can be used to measure the maximum flow velocity, Umax at the y-axis (vertical passing through the maximum point velocity in a channel cross section). The mean velocity of the cross section (U) was computed by φUmax, where φ was estimated from the field data collected with the cup-type current meter using the "two-point method".The flow discharge was then computed by multiplying the estimated flow area with (U). In contrast to the traditional method, where flow depth and flow velocity measurements are needed for each vertical, the proposed method has the advantages of short operation time and high accuracy. These features are especially important for the measurement of unsteady flow.