This study explores the landscape design of elevated roadside slopes in China’s mountainous cities, aiming to enhance urban environmental aesthetics through an integrated framework of aesthetic and ecological theories. By establishing an aesthetic evaluation system for main road slopes, the research analyzes factors influencing visual landscape quality— including plant configuration, geological conditions, and cultural context—and investigates their correlation with landscape art assessment. Treating mountain slopes as windows for urban civilization, cultural carriers, and ecological nodes, the study addresses the challenge of transforming municipal engineering slopes into symbols of urban humanity. The research integrates 200+ domestic and international literatures, field surveys of 15 main road slopes (over 2 km) in Chongqing, Guiyang, and Kunming, questionnaires from 300 road users and 50 designers, and 10+ local policy documents. Slopes were selected for geological representativeness, visibility (≤50 m from roads), safety (slope 80% through engineering-biological measures); and (4) effect monitoring (40% coverage increase and 30% erosion reduction within 6 months, with feedback-driven refinements). Findings show that the aesthetic-ecological design model balances visual appeal (e.g., seasonal color gradients) with ecological resilience (e.g., native vine soil fixation), validated by AHP-weighted morphological diversity as the primary aesthetic driver. The study provides a scientific framework for mountainous city slope landscaping, demonstrating its potential to reconcile urban development with environmental sustainability and offering a replicable model for similar regions.