To explore the adaptation of introduced Milu(Elaphurus davidianus), also known as Père David’s Deer, to their new environment, this study was designed to track and observe 16 Milu, which were released in the Dongting Lake wetland area from Jiangsu, from April 4 to May 12, 2016, using instantaneous scanning and recorded 486 observations. Nineteen types of behaviour were observed which were classified into nine categories: resting, feeding, moving, excreting, parental behaviour, embellishing, rutting, vigilance and social behaviour. This study analyzed the time-allotment and behavioural rhythms for resting, feeding, moving, and excreting categories. The result showed that before 9:00 and after 18:00 hours, the Miluwere almost always resting. Resting behaviour was exhibited and maintained at a high frequency in other periods as well. Fluctuations in feeding frequencies was consistent, peaks occurred after 14:00 hours when the frequency was the highest. Moving behaviour was split into a non-behaviour period, fluctuation period, low-ebb period, and peak period. Vigilant behaviour was influenced by external factors, and peaks appeared suddenly after the disturbance occurred. Resting behaviour occupied most of the daytime hours during the adaptive phase, and the proportion was higher than other behavioural types except two times, resting behaviour decreased after 13:00 hours when activity behaviour increased. The adaptation of Milu was documented to a certain extent, it was found that the animal’s behavioural rhythms changed during acclimation to the new habitat. It is likely that resting and feeding behaviours were influenced by temperature.