The placing of concrete interlocking blocks at the left edge of Langshansha in the 12.5 m deepwater channel downstream Nanjing of the Yangtze River phase I project encountered a flow rate of 2 m/s and water depth of up to 30 m, which made the acting force of concrete interlocking blocks quite complicated. Based on the finite element analysis of the acting force on the concrete interlocking blocks, we point out the relationship between the current force and the moving distance of the ship. Based on the analysis of the key points of deepwater construction,we optimization the design scheme.