Abstract: In order to study the influence of different altitudes on quality of Merlot and Cabernet Sauvignon wines from arid valley of Dadu River, the Merlot dry red wines from vineyards (2280, 2390 m) and the Cabernet Sauvignon dry red wines from vineyards (2280, 2390, 2600 m) were taken as research object, the physicochemical index, the phenolic content, antioxidant activities, ester aromatic substances and sense scores of sample wines were analyzed. The results showed that, along with the altitude increasing, the residual sugar contents in two wines (Merlot and Cabernet Sauvignon wines) decreased, while the contents of total acid, dry extract, total pehnolic, tannin, total flavonoid, total anthocyanin and chromaticity values, DPPH free radical-scavenging capacity and cupric reducing antioxidant capacity of two wines increased.The relative contents of ester in two wines decreased along with the increasing of altitude, altitudes had no effect on the composition of main ester aroma in two wines.By principal component analysis, the volatile esters of sample wines were extracted into three components with cumulative contribution rate reached 93.021%. Sense scores of two wines increased along with the altitude increasing, while too high altitude would have a negative effect on sensory quality, the Cabernet Sauvignon wines at the altitude of 2360 m had the best quality.The result of path analysis indicated that total phenolics had a direct and important impact on sensory quality.