To optimize the drainage performance of prefabricated grooved airport pavements, a three-dimensional numerical drainage model was established in ABAQUS and validated through laboratory drainage tests. Based on the numerical and experimental results, a parameter optimization method was developed. Lateral drainage capacity was taken as the primary evaluation criterion, while construction feasibility, groove-edge structural integrity, and joint waterproofing requirements were considered as engineering constraints. The effects of key macro-texture parameters, including groove spacing, groove width, groove depth, and groove chamfer, on the lateral drainage performance of the pavement were then systematically investigated. The results indicate that the drainage capacity of the pavement can be significantly improved by grooving. A negative correlation was observed between groove spacing and drainage performance: when the groove spacing was increased from 20 mm to 40 mm, the numerically predicted lateral drainage velocity and the experimentally measured flow velocity decreased by 28.11% and 31.03%, respectively. Positive correlations were identified for both groove width and groove depth. When the groove width was increased from 15 mm to 35 mm, the numerically predicted lateral drainage velocity and the experimentally measured flow velocity increased by 29.78% and 72.22%, respectively. When the groove depth was increased from 2 mm to 6 mm, the numerically predicted lateral drainage velocity and the experimentally measured flow velocity increased by 20.77% and 176.92%, respectively. Groove chamfer also affected drainage performance, but its sensitivity was relatively low. When the groove chamfer was increased from 25° to 90°, the numerically predicted lateral drainage velocity and the experimentally measured flow velocity decreased by 17.75% and 26.67%, respectively. The experimental and numerical results showed consistent variation trends and similar rankings of parameter sensitivity, although differences existed in their absolute values. This indicates that the proposed model is suitable for identifying drainage response trends and screening preliminary optimization ranges for grooved pavements. Under the combined constraints of drainage efficiency, construction controllability, groove-edge structural integrity, and joint waterproofing durability, the recommended parameter combination for prefabricated grooved airport pavements was determined as follows: a groove spacing of 28–30 mm, a groove width of 25 mm, a groove depth of 4 mm, and a groove chamfer of 45°–60°. This combination was not obtained by simply maximizing a single drainage indicator, but through a comprehensive balance among wet-condition aircraft operational safety, pavement drainage performance, and structural durability of prefabricated pavements. The findings can provide a theoretical basis and technical reference for parameter design, structural optimization, and engineering construction of prefabricated airport pavements.