<p>Despite the critical role of aggregate packing in asphalt mixture performance, the influence of aggregate morphology remains inadequately studied. This research investigates the underlying mechanisms by which morphology affects packing characteristics through combined macro and meso analysis. Laboratory experiments were carried out to measure the packing density of each grade of aggregate. The modified compressible packing model (CPM) was then presented to predict the packing density of asphalt mixtures featuring various aggregate morphologies. CPM accuracy was validated via numerical simulation. The mesoscopic parameters characterizing the packing characteristics were extracted by numerical simulation. It was found that increased sphericity elevates packing density, boosts average coordination number (indicating more particle contacts), and reduces inter-aggregate centroid spacing, promoting denser, more interconnected structures. A reduced Needle Flake Index (NFI) also increases packing density; however, it decreases the average coordination number while significantly reducing inter-aggregate spacing. This indicates a shift towards denser, yet less interlocked, configurations dominated by particle proximity over direct contact multiplicity. Crucially, the normalized distribution of inter-particle contact forces exhibits fundamental independence from particle shape, suggesting underlying universalities in force transmission despite morphological variations. The validated CPM proves robust for predicting macro packing density irrespective of morphology. More innovatively, the integrated experimental–numerical approach uniquely quantifies the divergent meso-scale pathways: enhanced contact and optimized proximity. These pathways illustrate how sphericity and NFI each contribute to optimizing packing density. These findings provide fundamental mechanistic insights for designing high-performance asphalt mixtures through targeted morphological control.</p>