Abstract: Hydraulic fracturing is a commonly used technique in mining engineering for rock fragmentation and modification, but when applied to composite rock layers with different lithologies, the propagation of hydraulic fractures exhibits significant interlayer effects. This study establishes a phase-field model for hydraulic fracturing in composite layered rocks, employing a dimension-reduced fracture flow and phase-field approach to characterize interlayer interfaces. The research systematically investigates the regulatory mechanisms of the stress conditions (stress difference and non-uniform loads), perforation angles, natural fractures, interface dip angles, rock layer stacking sequences and the size effect on fracture propagation behavior. The findings reveal that: (1) when the stress difference increases from low to high, the interlayer fluid pressure buildup effect weakens, promoting a transition of hydraulic fractures from interface-aligned propagation to interface-penetrating propagation. Non-uniform load distribution induces hydraulic fractures to preferentially interact with interfaces in low-stress zones. (2) A small perforation angle can expand the rock damage zone while weakening the unilateral fracture-arrest effect at interfaces. The natural fracture dip angle governs the fracture-interface interaction type, exhibiting either arrest-dominated behavior (θ ≤ 30° or ≥ 150°) or deflection-dominated connectivity (60° ≤ θ ≤ 120°). Interface dip angle intensifies fracture deflection and increases length as it rises from 0° to 60°, while no interaction occurs at 90°. (3) When rock layers transition from soft to hard formations with a stiffness ratio <1, the barrier effect of hard rock becomes prominent, causing hydraulic fractures to deflect and propagate along the interface. The size effect delays fracture-interface interaction time, and as model dimensions increase, the interaction behavior shifts from arrest to interface-aligned propagation. These results provide theoretical guidance and technical pathways for precisely controlling hydraulic fracture propagation in composite layered rocks．