As one of the key technologies for seamless linking up of rails, the aluminothermic welding technology is characterized by the simple equipment and convenient & efficient operation, so it has been used widely in the railway. However, the technology is rarely used in the rail welding in ports. Combining with the rail welding in the universal dock (phase 2) of Caofeidian port area, this paper introduces the basic principle,construction technology and effect of the aluminothermic welding technology, and proves the feasibility and operability of the technology, which may serve as a reference for the similar construction.