In order to understand the quality differences of Yunnan large leaf sun-dried green tea at different altitudes， the sensory evaluation， high performance liquid chromatography， simultaneous distillation extraction/gas chromatography-mass spectrometry combined with principal component analysis， orthogonal partial least square-discriminant analysis and other techniques and methods were used to compare the sensory quality， major biochemical components and volatile components of Yunnan large leaf sun-dried green tea at different altitudes in Wuliang Mountain. The results showed that the soup color of sun-dried green tea (H1) from 1 400 m to 1 800 m was lighter and brighter； the astringency of sun-blue tea (H2) from 1 800 m to 2 000 m was reduced and the umami taste was enhanced. The main biochemical and volatile components of H1 and H2 were significantly different； the contents of water extract， tea polyphenols， total catechins， gallic acid， phenol to ammonia ratio， GCG， ECG of H1 were significantly higher than those in H2； the contents of free amino acids， theanine， aspartic acid， glutamic acid， glycine， lysine， isoleucine and phenylalanine were significantly lower than those in H2. In addition， there were 17 volatile components in H1 and H2 with significant differences， namely， n-decanoic acid， chlorophyll alcohol， nonanal， trans-2-hexenal， heptanal， ethyl caproate， dehydrolinalool， diisobutyl phthalate， 1-hexanol， trans-nerolidol， farnesyl acetone， damascenone， geraniol， 4-methyl-3-penten-2-one， methyl linolenate， di-n-butyl phthalate， and nerolidol. This study will provide some reference value for the research on the effect of altitude on tea quality.