The phased array wave spectrometer is a small incident angle real aperture radar in the Ku band that detects ocean waves. When detecting ocean waves, it obtains a one-dimensional ocean wave spectrum in that direction by accumulating the echoes in different directions illuminated by the antenna. When the radar ring scans a circle to obtain the two-dimensional wave spectrum results. During the echo accumulation time in a single direction, the observation geometry of the phased array wave spectrometer can be simplified to flying along a straight trajectory at a fixed squint angle. During this period, the movement of the platform and the bending of the wave front will cause range migration of the echo signal, resulting in a decrease in the detection accuracy of the phased array wave spectrometer. In response to this problem, this paper analyzes the range migration phenomenon that exists in the detection of phased array wave spectrometers, and proposes a correction algorithm for the range migration of phased array wave spectrometers. The algorithm is verified using airborne flight test data. Comparing the backscattering coefficient and two-dimensional wave spectrum obtained by the traditional inversion algorithm and the range migration correction inversion algorithm, and comparing the measurement results with the buoy measurement results respectively, the results show that the range migration correction algorithm can effectively improve the accuracy of the wave spectrum retrieved by the phased array wave spectrometer.