The present invention discloses an expansion module connected to an ultrasound host. The expansion module includes a case, a first plug, a second plug, multiple probe slots, a path switching unit, and a control unit. The first plug is disposed on a first side of the case. The second plug is disposed on a second side of the case and matched with the first plug. The multiple probe slots are disposed on a third side of the case and coupled to one or more probes. The path switching unit is coupled to the first plug and probe slots. The control unit is coupled to the first plug, the second plug, and the path switching unit.
