A multilayer circuit board includes a first substrate and a second substrate in stack. The first substrate is provided with a first pad, a second pad, and a first sub-circuit. The first pad and the second pad are electrically connected to the first sub-circuit. The second substrate has a top surface, a bottom surface, and an opening. The bottom surface of the second substrate is attached to the top surface of the first substrate. The opening extends from the top surface to the bottom surface of the second substrate. The first pad of the first substrate is in the opening of the second substrate; the second pad of the first substrate is not covered by the second substrate. The second substrate further provided with a pad on the top surface and a second sub-circuit electrically connected to the pad of the second substrate.