Abstract: Carbon fiber reinforced plastics (CFRPs), as an advanced composite material, are widely used in engineering applications. However, research on the dynamic mechanical behavior of ultrathin CFRP laminates remains relatively limited. In this study, unidirectional ultrathin prepreg and hot-pressing molding processes were employed to fabricate ultrathin CFRP laminates with a single ply thickness of only 0.1 mm. The strain rate effects on specimens with five different ply orientations—0°, 90°, 0°/90°, 45°, and ±45°—were systematically investigated. Quasi-static compression tests indicated that the 45° ply orientation enhanced plastic behavior but reduced material strength and modulus, whereas the 90° ply orientation contributed to increased modulus and strength while reducing plastic deformation. Dynamic impact tests revealed that the 90° ply orientation improved both dynamic modulus and strength while decreasing yield strain. Although the 45° ply orientation reduced dynamic yield strength, it significantly increased the sensitivity of dynamic modulus and yield strain to strain rate. Compared with conventional CFRP laminates, the ultrathin CFRP composites developed in this study exhibited a 66% increase in fiber content per unit thickness; under the 0°/90° ply configuration, dynamic strength and modulus were enhanced by 123% and 926%, respectively. Based on the experimental data, a constitutive model for the ultrathin CFRP composites was established, and corresponding constitutive parameters were provided, offering a basis for predicting the mechanical behavior of CFRPs under different ply orientations and strain rates.