Abstract: The waveguide invariant, which describes the acoustic intensity interference pattern in ocean waveguide with a single scalar parameter. To estimate the moving target range based on the waveguide invariant, we need to know the source velocity. Aiming at the problem of rang estimation without knowing the target velocity, one kind of range estimation technique based on waveguide invariant by using velocity estimation with a horizontal line-array in shallow water was proposed. In this method, the slope of the LOFAR image is extracted by the HOUGH transform and the velocity is estimated by cross spectral analysis of the beam acoustic signals at different times, then the target range can be computed. Simulation results show that the proposed method can efficiently estimate the range of moving target. Using this method, the range of target ship was estimated by using the shallow water trial data in July 2013. The maximum relative error of target range estimates is smaller than 10% compared with GPS values.