The open burst mode is a kind of Synthetic Aperture Radar （SAR） altimeter operation mode with alternating receiving and transmitting pulses. This mode allows for a greater number of independent pulses in a unit time than the closed burst mode of a satellite altimeter such as the Sentinel-3， thereby improving range precision. However， because the Pulse Repetition Frequency （PRF） of this mode is less than the Doppler bandwidth， the azimuthal Doppler spectrum is aliased and the resulting multi-looking echoes are distorted， thus reducing the range precision. By studying the correspondence between the range curvature and the aliasing frequency in the processing of synthetic aperture signals， an open burst anti-aliasing filtering method based on multi-looking beam stack processing is proposed to filter the multi-looking beam stack and effectively solve the azimuthal aliasing effect of the open burst mode. The proposed method can effectively improve the range accuracy through simulation. At a significant wave height of 2 m， the 1 Hz range precision of the open burst anti-aliasing filtering method improves from 0.7 cm to 0.60 cm， an improvement of 14 %.