In order to explore the development of under-ice stratification and its impacts on the lake metabolic rates, the meteorology, ice and snow processes and under-ice water temperature and dissolved oxygen (DO) were observed in Lake Wuliangsuhai during winters of 2016-2019. This paper presented the under-ice water temperature and DO dynamics, and characterized the mixing appearance and evolution and its influence on lake ecosystem metabolic rates. The results indicated that the bulk water temperature was relatively high (up to 10℃) in freezing Lake Wuliangsuhai, and the thermal structure was featured by a stable inversion layer at the top and a weak inversion layer at the middle-bottom during freezing period, but by an inversion top layer and a mixed mid-bottom layer during melting period. Because of the salinity profile, the mixing took place in the middle-bottom water when its temperature grew up over approximately 6-8℃, and from then the mixing layer expanded fast as the incident solar radiation increased. The under-ice DO roughly decreased from the top to the bottom of the water column, and even formed a bottom anoxic zone (< 2 mg/L). DO amount dynamics was governed by the balance of photosynthesis production and respiration consumption, both of which were influenced by the ice/snow conditions, radiation transmission, water temperature and mixing process. In particular, the mixing events were able to directly change the temperature stratification and accelerate photosynthesis and respiration rates, and thus change the DO structure.