The expulsion of interstitial liquid from the crystal mush is closely related to the abundant crystallization of Fe-Ti oxides during the mid-late stage of the solidification of layered intrusions, yet the expulsion mechanism of interstitial liquid before the abundant crystallization of Fe-Ti oxides at the early stage is still enigmatic. The highly differentiated Bijigou intrusion in the northern margin of the Yangtze block is the largest layered intrusion with Fe-Ti-(V) mineralization in China at present. The lower zone (LZ), middle zone (MZ) and upper zone (UZ) of the Bijigou intrusion are mainly composed of plagioclase peridotite, gabbro and diorite, respectively. In this study, we analyzed the crystal size distributions (CSDs) and spatial distribution patterns (SDPs) for plagioclase and clinopyroxene of samples from the plagioclase peridotite unit in the LZ, in order to examine the expulsion mechanism of interstitial liquid from the crystal mush at the early stage of solidification of layered intrusions. Modeling results show that the fraction of trapped liquid (FTL) is 9% ~ 13% for samples from the plagioclase peridotite unit of the Bijigou intrusion, suggesting the interstitial liquid was effectively expelled from the crystal mush. The consistent slopes of the CSD curves for clinopyroxene and plagioclase of samples from the plagioclase peridotite unit mainly vary from ?3.36 to ?2.45 and from ?2.99 to ?1.87, respectively, and the variable intercepts are from 0.45 to 3.35 and from 1.06 to 2.83, respectively, similar to those for the mechanical compaction. In addition, the SDP R value (ratio of observed and predicted nearest neighbor distance of the same mineral) and the mineral mode except plagioclase/clinopyroxene of the samples are negatively correlated, consistent with the trend of mechanical compaction. Therefore, the expulsion of interstitial liquid at the early stage of solidification of the Bijigou intrusion is controlled by mechanical compaction. On the other hand, we compared the Bijigou intrusion with the Skaergaar, Sept Iles and Kiglapait layered intrusions in terms of the scale, fraction of trapped liquid, density contrast of the interstitial liquid and cumulus crystal, the relationship of accumulation rate and compaction rate, and the thickness of mush layer. We propose that the compaction plays a critical role in expelling the interstitial liquid at the early stage of solidification of layered intrusions if there’s no magma replenishment and convection, but the factors controlling the degree of compaction are distinct in different conditions. When the intrusion sizes are comparable, the onset of compaction is mainly controlled by the density contrast of interstitial liquid and cumulus crystals, with a higher degree of compaction for a greater density contrast. In addition, compaction is more likely to operate in large intrusions, rather than small ones at the early stage of solidification.