A bridge system for installing electronic appliance to light source socket and a bridge method are disclosed. The system includes a light source plug, a power line communication module and a connection unit. The light source plug is electrically connected to the light source socket to perform data communication through the power lines. The power line communication module is electrically connected to the light source plug to convert AC power into DC power and perform analog-to-digital data conversion simultaneously through the power lines. The connection unit is electrically connected to the electronic appliance to provide AC or DC power and transmit converted digital data to the electronic appliance. Accordingly, there is no need to add power cables or power adapters.