In order to determine the best shelf life of the atemoya, the changes in the biochemical characteristics in five different stages of senescence were investigated. During postharvest ripening at room temperature, the firmness decreased rapidly after harvest and the fruit weight loss and browning degree increased from the earliest green-colored stage onward. The total soluble solid concentrations (TSSC) and titratable acidity (TA) increased continuously throughout maturation, and the peak respiratory and ethylene production rates occurred on the 3d and 5th day of postharvest, respectively. Phenylalanine ammonialyase (PAL) activity steadily increased, catalase and polyphenol oxidase (PPO) activities decreased significantly on the 1st day and then gradually increased, and peroxidase activities increased during the initial 3 days, and then decreased at later stages. The volatile fingerprints of flesh samples from the five senescence stages were successfully established using gas chromatography-ion mobility spectrometry (GC-IMS) combined with principal component analysis, and 32 typical target compounds and 35 indeterminate compounds were obtained. The results provide a theoretical basis for the development of innovative preservation methods for atemoya.