Abstract: A method for estimating flight path of low altitude target was presented, which required a single acoustic array. It estimated the flight parameters of the target of narrowband acoustic source which kept its velocity and height constant based on Doppler effect. By combining these flight parameters with Direction-of-Arrival estimations, the path direction, horizontal offset and height were estimated, and then the flight path of the target was determined according to a geometry model. The effect of the signal propagation delay on the flight path estimation error was also analyzed and corrected in this method. Simulation and field method, and it realized flight path estimation experiment data were analyzed to verify the effectiveness of the proposed with single acoustic array with small aperture