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