Abstract: This study addresses the challenges associated with high-viscosity polyphenylene sulfide (PPS) melt, which often fails to adequately impregnate continuous carbon fiber (CF) woven fabrics, resulting in CF/PPS composites formed by compression molding that exhibit high porosity, uneven resin distribution, and significant thickness variations. To mitigate these issues, a room-temperature pre-pressing process prior to molding was proposed. By actively regulating the interlaminar nesting displacement of multilayer plain-woven fabrics before resin melting, this process alters the initial stacking structure of the fiber preforms, thereby optimizing resin infiltration and defect elimination during subsequent molding. This work investigates the effects of high-temperature desizing treatment on the fabric structure of CF plain fabrics, as well as the effects of pre-pressing pressure at room temperature on the microstructure, nesting displacement, thickness evolution, and mechanicalproperties of PPS composite laminates reinforced with desized and non-desized CF plain fabrics. The results indicate that moderate room-temperature pre-pressing (0.1 MPa) significantly reduces composite porosity, particularly interlaminar porosity, minimizes resin-rich zones, and leads to notable improvements in flexural strength and interlaminar shear strength (ILSS), with maximum increases of 56.21% and 70.14%, respectively. However, excessive pre-pressing pressure (0.5 MPa) causes the originally well-ordered non-desized fabric structure to become overly compact, hindering further impregnation and degassing during subsequent molding, ultimately resulting in increased porosity and reduced mechanical performance. In contrast, for the inherently looser desized fabrics, a pre-pressing pressure of 0.5 MPa continues to enhance impregnation. The nesting displacement theoretical model established in this study effectively describes the correlation between the nesting effect induced by pre-pressing and the final laminate thickness, thus clarifying the mechanism by which room-temperature pre-pressing enables control over the forming quality and performance of CF/PPS composites. This work provides an optimized strategy for efficient, low-defect molding of high-performance thermoplastic composites.