A transmission cable includes a cable (20) and a plug (10). The cable includes a communication line (22), a power line (26), a plurality of inner jackets, an outer jacket wrapping the communication line and the power line together, and a metallic jacket for wrapping the communication line. The power line includes a plurality of power conductors, and each of the power conductors is wrapped by one of the inner jackets. The communication line includes a plurality of communication conductors, and each of the communication conductors is wrapped by one of the inner jackets. The plug includes a shell (12), a socket (14) and a plurality of pins (16) disposed in the socket. Each of the communication conductors electrically connects with one of the pins respectively, one of the power conductors electrically connects with pins of the remaining pins, and the metallic jacket is electrically connected to the shell.