Based on the dredging site data of year 2013 to 2015 in the south passage waterway,we analyze the maintenance features of the 5.5 m navigation channel of South Passage,and discuss the further maintenance situation of the navigation channel.The results show that the maintenance of the 5.5 m navigation channel of south passage is generally kept in a good situation during the past 3 years,and its maintenance features are mainly as follows:1)the dredging location of navigation channel is mainly in the local shallow region near the Jiuduan Lightship;2)the in-year sedimentation of the 5.5 m navigation channel has seasonal differences with siltation in the flood season and erosion in the dry season;3)the existing depth of navigation channel is not easily affected by typhoon-induced sudden siltation.In view of the characteristics of 5.5 m channel maintenance at the present stage,it will keep in good situation of easy maintenance for the south passage waterway.