A signal transmission structure is provided. The signal transmission structure includes a circuit board, a coaxial cable connector, and a conductive layer; the aforementioned circuit board includes at least one alignment through hole, a signal pad, and a signal trace connected to the signal pad. Additionally, the signal pad and the signal trace are disposed on a surface of the circuit board. In addition, the alignment through hole passes through the circuit board. The coaxial cable connector is located on a surface of the circuit board. The coaxial cable connector has a signal pin and at least an alignment pin, and the alignment pin is inserted into the alignment through hole. The conductive layer is located between one end of the signal pin and the signal pad, and the signal pin is electrically connected to the signal pad via the conductive layer.