In order to probe into the internal mechanism of dissolved oxygen (DO) equilibrium in the shallow Lake Wuliangsuhai in Northern China during the ice-covered period, a set of online water monitoring buoys were arranged in the center of lake for collection of water quality data from January to February, 2021. Upon the wavelet denoising processing of DO and based on the meteorological data, the DO changes during the growth and stability period of ice was simulated and analyzed, followed by a qualitative analysis of the mechanism of the DO equilibrium. Results show as follow: The lake's maximum daily average oxygen production rate was 7.19 mg/(L ·d); the minimum was 2.01 mg/(L ·d). The maximum daily oxygen consumption rate was 7.13 mg/(L ·d) and the minimum was 2.37 mg/(L ·d). The maximum 24-hour per-unit-time average oxygen production rate was 0.55 mg/(L ·h) and the minimum was 0 mg/(L ·d). The maximum per-unit-time average oxygen consumption rate was 0.36 mg/(L ·h) and the minimum was 0.08 mg/(L ·h). This study indicates that the disequilibrium between the DO production and consumption on small time scales results in DO disequilibrium on large time scales, causing oxygen deficiency in the lake in winter. Further analysis on the relationship between DO driving factors and water environment factors suggests a negative correlation between turbidity, water temperature and oxygen production rate and a positive correlation between chlorophyll-a and oxygen production and consumption rate, which indicates that these restrictive water environmental factors influence the DO equilibrium in water body under ice.