A device, a system, and a method for testing a PCB are provided. The PCB includes a first electrical contact and is applied to a display panel. The device includes a test board, a display assembly, a circuit unit, an aligning portion, and a pressing portion. The PCB and the display assembly are positioned on the test board. One end of the circuit unit defines a second electrical contact, and the other end of the circuit unit defines a third electrical contact. The aligning portion is configured to align the first and the second electrical contacts. The third electrical contact is electrically communicated with the display assembly via an electrically conductive adhesive. The pressing portion is configured to press the circuit unit, so that the second electrical contact is electrically connected with the first electrical contact and the display assembly is electrically communicated with the PCB.