  We present the first polarimetric analysis of Quasi-Periodic Oscillations
(QPO) in a black hole binary utilizing \textit{IXPE} data. Our study focuses on
Swift J1727.8--1613, which experienced a massive outburst that was observed by
various telescopes across different wavelengths. The \textit{IXPE} observation
we studied was conducted during the Hard-Intermediate state. The polarization
degree (PD) and polarization angle (PA) were measured at 4.28$\pm$0.20\% and
$1.9^{\circ}\pm1.4^{\circ}$, respectively. Remarkably, significant QPO signals
were detected during this observation, with a QPO frequency of approximately
1.34 Hz and a fractional root-mean-square (RMS) amplitude of about 12.3\%.
Furthermore, we conducted a phase-resolved analysis of the QPO using the
Hilbert-Huang transform technique. The photon index showed a strong modulation
with respect to the QPO phase. In contrast, the PD and PA exhibit no
modulations in relation to the QPO phase, which is inconsistent with the
expectation of the Lense-Thirring precession of the inner flow. Further
theoretical studies are needed to conform with the observational results.
