Researching and improving the large placing ship’s mobile truss gantry crane hoisting interlocking pieces of construction equipment，super-short base line underwater mattress locating technology and underwater mattress molding status detecting technology,etc.,we can raise the efficiency of super-long bottom protection mattress’s laying construction，with real-time dynamic positioning precision of mattress position during the laying underwater，and detect the mattress’s underwater smoothness and state of overlapping,to meet the needs of the project.