Shenzhen Port Tonggu Channel is the main access for large cargo ships to the major ports in Shenzhen.In view of the influence of grappling dredger construction on the safe navigation,we calculate the safe distance of the navigation vessels and determine the grappling dredger construction scheme.Under the prerequisite of guaranteeing the safe navigation of vessels,we can improve the construction efficiency of the grappling dredger.By the precise positioning and reasonable avoidance program,we ensure the smooth construction and safe navigation.