The disclosure discloses a timing controller board, a main control board, a display device and a detection method thereof. The timing controller board outputs a second level signal transmitted by a first fixed potential signal pin to the main control board through a detection circuit when a first data signal pin outputs a first level signal; the main control board loads a second potential signal transmitted by a second fixed potential signal pin to a second data signal pin and a clock signal pin through a switching circuit upon receiving the second level signal, to cause the main control board to stop sending a data signal to the timing controller board through the second data signal pin and stop sending a clock signal to the timing controller board through the clock signal pin.