The embodiments of the present disclosure relate to a display device, a test circuit, and a test method thereof. More specifically, a display device may include a silicon substrate having a plurality of gate lines, a plurality of data lines, a plurality of sensing lines, and a pixel array on which a plurality of subpixels are arranged; a test circuit arranged on the silicon substrate, the test circuit configured to select at least one line of the plurality of data lines or the plurality of sensing lines, to convert a signal transmitted through the selected line into a digital signal, and to output test data; and a test pad unit configured to output the test data to a circuit outside the silicon substrate.