Abstract: The gradient coloration of ethylene-degreened mandarin fruit was studied. The results indicated that the coloration process of stem end position of the peel was faster than the equator position during the degreening process. The difference of chlorophyll content and carotenoid content of these two positions could well explain this phenomenon. Further studies indicated that the degradation of chlorophyll a and chlorophyll b in the stem end position of ethylene-degreened mandarin fruit was faster than that in the equator position，more orange-colored carotenoids（mainly β-cryptoxanthin）were synthesized in the stem end position of ethylene-degreened mandarin fruit，while more yellow-colored carotenoids（mainly lutein）were synthesized in the equator position. The different expression levels of some regulatory genes in chlorophyll and carotenoid metabolism（including CitChlase，CitNYC，CitPDS，CitCHYB，CitNCED1 and CitNCED2）could explain the pigment changes of these positions to some extent.

Key words: Mandarin fruit, postharvest, differences of coloration, pigment metabolism, ethylene, degreening treatment