Abstract: Based on every 5 minutes visibility monitoring data from 2018 to 2020 from 26 automatic weather monitoring stations along the Chongqing section of Yangtze River (CSYR), data of the jurisdicted water area of Chongqing Maritime Safety Service and the basic geographic information of Yangtze River, the spatiotemporal distribution and temporal morphological characteristics of the fog in the CSYR are analyzed by using machine learning algorithms such as K-means, DTW and PCA. The results show that the high incidence area of fog processes in the CSYR is the waters from Fuling to Zhongxian, followed by Changshou and its upstream waters. Fog process is more frequent in June and July, whereas less in winter. Fog usually rises and disperses at night, and the majority of fog processes has a duration within one hour. Processes with different lifespan present distinct temporal morphological characteristics. In the cases that last for less than 27 hours, signals of visibility decline are found, whereas the cases which last for more than 27 hours mainly show signals of visibility rise. In addition, the early oscillation signal that looks like elephant trunks is further enhanced with the extension of the fog process duration.