Abstract: This study employs cyclostratigraphic methods to investigate the Hanjiang Formation in the Xijiang Sag of the Pearl River Mouth Basin. Using natural gamma-ray logging data as the paleoclimate proxy and integrating time series analysis techniques, we identified astronomical orbital signals and extract the 405 ka long eccentricity cycle using Gaussian bandpass filtering to construct a high-precision astronomical time scale. We applied the sedimentary noise models (DYNOT and ρ1 models), reconstructed relative sea-level changes, and combined lithological and logging curve characteristics, based on which high-frequency sequence stratigraphic division of the Hanjiang Formation was conducted. Results demonstrate that the Hanjiang Formation was controlled by astronomical orbital cycles, with a depositional duration of 6.08 Ma and an optimal sedimentation rate of 20 cm/ka. Through astronomical tuning, a high-resolution astronomical time scale spanning from 16.17 Ma to 10.09 Ma was established, dividing the formation into 15 fourth-order sequences and 64 fifth-order sequences. This study highlights the critical role of sea-level fluctuations and sedimentation rates in the development of sand bodies during the Middle Miocene. This research not only provided a methodological support for understanding the sedimentary facies differentiation, sequence stacking patterns, and reservoir development of the Hanjiang Formation, but also confirmed the significance of Milankovitch cycles in high-resolution stratigraphic studies, offering new scientific insights and technical approaches for reservoir prediction and evaluation in the hydrocarbon exploration of the Pearl River Mouth Basin.