In second section of the first phase of the construction of the 12.5 m deep water channel construction project in the Yangtze River below Nanjing,there is a wide range of soft mattress laying in transition between the high beach and deep water.Aiming at the problem of how to realize the one-time laying of the steep slope section of the shoal,we study and discuss the ship selection and construction method,and apply the construction technology of soft mattress by abutting joint laying for soft shoal and steep slope.The technology achieves the one-time laying of the high shoal and the deep water transition section,avoids the possible quality problems which may lead to the split amplitude lap joint.It can effectively guarantee the quality of the construction,and can provide reference for the similar projects.