A method for separating echo signals of Space-Time Waveform Encoding Synthetic Aperture Radar, STWE SAR, in elevation, characterized by comprising: receiving aliasing echo signals of a plurality of sub-swaths; for a target sub-swath of the plurality of sub-swaths, generating a plurality of sub-beams associated with the target sub-swath, the plurality of sub-beams pointing to different directions of the target sub-swath respectively, and a null of each of the plurality of sub-beams being used for deep nulling suppression on echo signals of sub-swaths except the target sub-swath; and processing the aliasing echo signals based on the plurality of sub-beams and a plurality of nulls corresponding to the plurality of sub-beams to generate a target echo signal of the target sub-swath, comprising: for each of the plurality of sub-beams, extracting a partial echo signal of the target sub-swath from the aliasing echo signals by use of the sub-beam, and performing deep nulling suppression on the echo signals of the sub-swaths except the target sub-swath by use of the null of the sub-beam; extracting a plurality of partial echo signals of the target sub-swath from the aliasing echo signals by use of the plurality of sub-beams; and filtering the plurality of partial echo signals, and synthesizing the plurality of filtered partial echo signals to obtain the target echo signal of the target sub-swath. receiving aliasing echo signals of a plurality of sub-swaths; for a target sub-swath of the plurality of sub-swaths, generating a plurality of sub-beams associated with the target sub-swath, the plurality of sub-beams pointing to different directions of the target sub-swath respectively, and a null of each of the plurality of sub-beams being used for deep nulling suppression on echo signals of sub-swaths except the target sub-swath; and processing the aliasing echo signals based on the plurality of sub-beams and a plurality of nulls corresponding to the plurality of sub-beams to generate a target echo signal of the target sub-swath, comprising: for each of the plurality of sub-beams, extracting a partial echo signal of the target sub-swath from the aliasing echo signals by use of the sub-beam, and performing deep nulling suppression on the echo signals of the sub-swaths except the target sub-swath by use of the null of the sub-beam; extracting a plurality of partial echo signals of the target sub-swath from the aliasing echo signals by use of the plurality of sub-beams; and filtering the plurality of partial echo signals, and synthesizing the plurality of filtered partial echo signals to obtain the target echo signal of the target sub-swath. for each of the plurality of sub-beams, extracting a partial echo signal of the target sub-swath from the aliasing echo signals by use of the sub-beam, and performing deep nulling suppression on the echo signals of the sub-swaths except the target sub-swath by use of the null of the sub-beam; extracting a plurality of partial echo signals of the target sub-swath from the aliasing echo signals by use of the plurality of sub-beams; and filtering the plurality of partial echo signals, and synthesizing the plurality of filtered partial echo signals to obtain the target echo signal of the target sub-swath.