<p>To clarify the environmental and economic impact differences between asphalt and composite pavements, this study proposes a quantitative assessment framework of "environmental-economic" two-dimensional dimensions, incorporating the uncertainty of assessment results into this framework. First, a life cycle assessment model was constructed based on SimaPro; second, environmental governance costs were integrated into the life cycle cost to establish a cost assessment model considering external environmental costs; finally, the pedigree matrix combined with Monte Carlo simulation was used to quantify the randomness of input parameters on assessment results. The research results show that compared with asphalt pavements, composite pavements exhibit higher environmental impacts in terms of global warming, ozone formation, terrestrial acidification, freshwater eutrophication, and freshwater ecotoxicity. From an economic perspective, the combined effect of material costs and environmental costs leads to a higher total construction phase cost for composite pavements. The Monte Carlo simulation results indicate that the uncertainty analysis results are consistent with those of deterministic analysis, and the fluctuation ranges of the five environmental indicators for composite pavements are slightly higher than those for asphalt pavements. The findings provide references for low-carbon material selection in highway construction, optimization of construction processes, and formulation of targeted emission reduction strategies.</p>