The invention discloses a ship cascade T-connection box for ships alongside. The box comprise an incoming line socket, two power supply sockets and a main controller, the two power supply sockets arerespectively marked as a first power supply socket and a second power supply socket; each of the incoming line socket, the first power supply socket and the second power supply socket comprises 8 terminals, wherein 3 terminals of the 8 terminals are taken as phase line terminals, 2 terminals of the 8 terminals are taken as communication terminals, and 2 terminals of the 8 terminals are secondary terminals; the phase line terminals of the incoming line socket are accessed with a busbar, the output of the busbar is divided into two paths, one path is connected with the phase line terminal of thefirst power supply socket, and the other path is connected with the phase line terminal of the second power supply socket; the communication terminals of the incoming line socket are connected with the communication interfaces of the main controller and the communication terminals of the second power supply socket; and the secondary terminals of the incoming line socket are connected in series tothe two ends of an emergency stop loop. When the system supplies power, each ship alongside only needs to use a power supply cable connected with the T-connection box of an adjacent ship to obtain ashore power supply so as to increase the practicability.