  In this paper, we propose a novel method for distinguishing extraterrestrial
intelligence (ETI) signals from radio frequency interference (RFI) by
leveraging polarization features. We exploit the sinusoidal variation of the
linearly polarized components of Stokes parameters with the parallactic angle
as a characteristic signature of ETI signals, while such linearly polarized
components remain relatively stable for terrestrial RFI. Typically, a minimum
of 4-8 hours of observation time is required to detect these sinusoidal
variations. The polarization approach in the search for extraterrestrial
intelligence (SETI) also enables us to study the radio stellar bursts emitted
by M-type stars as ancillary science, which is relevant to assessing the
habitability of exoplanets. Compared to the frequency drift method, the
polarization method effectively reduces the required observation time for
signal identification while improving the signal identification process.
