A coastal engineering ship positioning device belongs to water engineering building construction equipment and comprises a reference station, a mobile station, a depth finder, an industrial computer, a digital transmission radio and a global position system (GPS) receiver. The reference station is a fixed satellite signal acquisition point set on shore or an island, the mobile station is a satellite signal acquisition point set on a ship, the reference station transmits acquired real-time satellite signals to the mobile station, and the industrial computer calculates various signals, controls taking-up and paying-off of four anchor cables duly and adjusts the correct position of the ship. The coastal engineering ship positioning device has the advantages of high positioning precision without being affected by tide and weather conditions, all-weather construction and fine working stability, and is applicable to various coastal engineering such as sea reclamation, ports, wharfs, fishing, dredging, submarine pipelines, artificial islands and the like.